I believe, basing on ReallyGoodPie's answer, I do know something that would work most of the time.
Unless you're a devout traveler and wandered for days away from the spawn point (not too smart, a creeper blows up you and your bed and you're back to spawn, days away from home - not to mention all three strongholds are between 640 and 1152 blocks from the spawn) we can assume your Nether Portal was somewhere within, say, 3200 blocks radius from 0,y,0 (that's like 9 maximum zoom-out maps!). Since coordinates in Nether are an eighth of the Overworld, that means the portal will be within 400 blocks from 0,y,0 (and you can estimate the radius by estimating the distance of the overworld portal from spawn.) You can also estimate the altitude (y) - 64 if that was the surface, more for hills, less for underground.
Now locate 0,y,0 using F3 and then travel in spiral around that point, trying to explore increasingly wider circle of terrain and controlling your distance using the coordinates. That way you shouldn't miss any terrain and be able to locate familiar areas and eventually the portal - 25 chunks radius isn't something beyond hope for exploring, and most people will have their homes (and portals) within 1000 radius, that's mere 8 chunks of Nether away from Spawn. (and if you remembered rough direction of your portal from spawn, using the Cobblestone Compass trick you can head straight for your portal from the "origin")
Another option, inspired by Loren: If you have enough wood, or a chest - or are near enough from the portal (say, aforementioned 0,y,0) - or are patient enough to locate a treasure chest at a fortress - write down your coords, dump all your equipment, suicide, then go, retrieve it all - stopping long enough to take note of the portal location this time.
There is a list of Mappers on the Minecraft Wiki.
There are not too many that work with 1.8, but I will list a few that seem to work for your problem:
MCAMap is a tool that I have used before. All you need to do is point it to the world folder and render all the region files. Make sure not to make the quality too good, or it will take some time to render. Officially, it supports only 14w11b, though I don't see why the 1.8 release version wouldn't work.
uNmINeD seems like a very nice mapping software, 1.8 is officially supported. I haven't actually used it though, so I can only vouch for it based on nice screenshots. No idea as to the speed as well.
Minutor Reasonably quick and straightforward. 1.8 supported. You have to open the world folder rather than a level.dat
Best Answer
To craft a map from scratch, you need nine sugar cane (every three pieces of sugar cane makes three sheets of paper), four iron ore, fuel to smelt that ore, a piece of Redstone (requires an iron pickaxe or better) and access to a crafting table and furnace.
You can also zoom out the map by adding 8 more pieces of paper and the map itself in a crafting table.
You can also clone the map by adding another empty map with the map you want to clone in the crafting table.