http://www.tastespotting.com is everything you need. You will get hundreds of ideas there.
Also, remember what the director of my culinary school says: "Food should look like it fell from Heaven onto the plate." Don't get too fussy in other words.
Editing to add a more complete answer.
The ability to plate effectively and beautifully is a combination of two things: an artistic eye and technical skill.
The latter I will deal with in a moment. The former requires some inborn talent, but it can be nurtured. Teach yourself about basic visual concepts such as proportion (how things relate to each other in size), contrast, and negative versus positive space (positive space is the space actually taken up by what you are working with; negative space is the empty space. Much as in music, it's the spaces between the notes that bring interest to the whole assemblage).
Then start paying attention to the plates you see. What do you like about them? What don't you like. Then go out, buy some play-doh, make some food-shaped things and some sauces of various consistencies, and start playing with your plates. A note: almost every fine dining restaurant in the world uses white plates exclusively. There is a reason for this; it shows the food off better. That being said, there is a time and a place to break that fashion. Sometimes for tradition (charcuterie and cheese plates are often served on wooden boards) and sometimes for dramatic effect (a pure white cream soup in a black bowl, e.g.)
Now, on to technical skill. The first and most important thing to do is think about how you are going to plate the final dish before you even start prep. This thinking will inform how you cut your products, what shapes you are looking for, and what consistency you want your sauces to be. It will also inform how you prepare your garnishes--are you looking for something upright and dramatic? Something smeared across the plate? You need to plan ahead, and that means careful knife skills and sauce work. Keep colours in mind, too!
Then you need to start practicing on how you sauce your plates. Thinner sauces/flavoured oils will spread. Thicker sauces and purees stay in place, and thus can be shaped. The first real skill I learned for saucing a plate is using a thick puree, dropping a dollop on the plate, then quickly smearing with the back of a spoon. When done right, it can be very pretty, and for that reason is quite common. it's also the sort of thing you only tend to see at restaurants, to it often impresses dinner guests at home. The easiest way to practice this technique is with homemade mayonnaise.
You will also want to invest in a couple of squeeze bottles. This will allow you to place (thick) sauces wherever and however you want. Again, mayonnaise is a perfect consistency to practice with. Just whip up a batch and spend your afternoon playing.
Also, if you're putting sauce on the plate with a spoon, use the spoon end-on, don't drop it from the side of the spoon.. You will have much more control this way.
Then comes the rest of the food you're putting on the plate. With anything that has been fried, sauteed, or roasted with juices, always pat the bottom dry on some paper towel first, to prevent runoff on the plate (unless of course that is what you want). Tongs are invaluable until you get your fingers to a point that they can tolerate relatively high heat. And always remember: once you place something, that's it. Moving it around will cause mess and problems.
For more advanced techniques, look at things like ring molds (for packing loose products together) which are available in a wide variety of shapes. Plain tin cookie cutters also work very well for this purpose, and are FAR cheaper than ring molds. Also teach yourself to make quenelles, the football-shaped blobs made by shaping something soft in two spoons.
Hopefully that all helps.
Best Answer
IMO, this really would have greater lasting value with a single detailed answer instead of a poll. Here's an annotated list of all the recommendations so far:
On Food And Cooking (Harold McGee) is all science at a very detailed level, combining food chemistry and biology and explaining the interactions between ingredients and the mechanisms behind various cooking methods. If you're looking for a pure science book, this is it.
Good Eats: The Early Years and Good Eats 2: The Middle Years by Alton Brown. His books are less technical/scientific than other authors and tend to focus more on application, making them more accessible to less hardcore cooks.
CookWise (Shirley O. Corriher). Written by a biochemist who has done a lot of consulting in the food industry. This is more practical than McGee and more technical than Alton's books. It also includes a ton of recipes, which can be a good thing or bad thing depending on your personal preferences. She has also written a baking version, BakeWise.
Molecular Gastronomy (Hervé This, translated by Malcolm DeBevoise). This is more of a niche book (about - surprise - Molecular Gastronomy) and as you might expect is a little French-centric. What's really great about this book is how it debunks a lot of popular cooking myths with actual controlled experiments and hard data. It wouldn't be my first choice to recommend to a Food Science newbie, but nevertheless a good one to add to your collection.
The Fat Duck Cookbook (Heston Blumenthal). Written by the founder of the Fat Duck Restaurant in the UK. It's about the history of the Fat Duck and has a big recipe collection (from the restaurant, obviously) and a section at the end dedicated to food science. This one's really for the advanced crowd as it involves a lot of molecular gastronomy, sous-vide and other esoterica - complex preparations, hard-to-find ingredients and unusual/expensive equipment.
Cooking for Geeks (Jeff Potter) is, as the title implies, written to appeal to geeks, and as such has a certain amount of science but tends to be quite a bit more basic as far as actual cooking technique goes. It's more "applied science." Honestly, I wouldn't recommend this for very experienced cooks, but it's great for getting into cooking and gaining an enthusiasm for it (if you're kind of a geek).
Cooking for Engineers is a web site, not a book, which has the obvious advantage of being free and searchable. It's hard to really define this as its scope is so wide, but I will say that I've found it to be a surprisingly useful and detailed resource whenever I need to find out something quickly.
What Einstein Told His Cook (Robert L. Wolke) is also mostly on the science itself but is written to be more accessible to the layperson. As one reviewer on Amazon put it, Wolke is like the Bill Nye of Food Science. One part science, two parts entertainment. Another member has criticized it for making unproven claims (particularly on nutrition).
The Cooks Illustrated annuals (from America's Test Kitchen) are less about the actual chemistry of food but do highlight a very scientific approach to cooking based on up-front research, experimentation and testing. See David LeBauer's Answer for a more detailed explanation.
The Science of Cooking (Peter Barham) focuses on the chemistry and physics of why some recipes work and some fail.
khymos.org - on the surface it's about molecular gastronomy, but you'll find much of the science of cooking (e.g. the chemistry behind "working" flavour pairings etc) on there too.
The Food Lab: Better Home Cooking Through Science (J. Kenji López-Alt) is a collection of detailed recipes, tips and explanations. It's written to be easily accessible to a chef without much experience.
Serious Eats is a website with both recipes and stories about how the recipes were developed (often with pictures of various attempts to compare how changing processes or ingredients affected things). Especially see the 'techniques' section of The Food Lab