Travel Devotion is, by orders of magnitude, your best option
Losing some BAB, HP, perhaps skills, Skirmish damage, and Favored Enemy bonuses... are all worth it for what that single level of cleric can get you. Travel Devotion straight-up solves your movement problem, which not much else can say.
Pounce does not work
Charges specify melee attacks, so Pounce is useless to you. Swift Hunters can use Pounce, mind, but with melee attacks.
Greater Manyshot is deep down the feat tree, but works
Greater Manyshot makes each shot from Manyshot a real attack, letting you deal Skirmish damage on each one. Excellent solution, but at the cost of four feats.
Mounted Full Attack might work, but is very expensive
Some prestige classes give you the ability to make a full-attack while your mount moves. If you ignore the utterly stupid errata for Skirmish, which prevents using it based on mount movement, it could work.
Cavalier or halfling outrider (Complete Warrior), for instance. This route will take many feats and take a very long time (Cavalier requires four feats, most of which are useless to you, and gets it at 6th, while the halfling outrider requires two feats you might actually want, but doesn’t get it until 8th). Ashworm dragoon (Sandstorm) splits the difference with two feats, one kind of useless to you, and getting it at 7th, plus it gives you a decent mount.
Magic, psionics, mysteries
Hustle and dimension hop are low-level psionic powers that allow swift-action movement, knight’s move is a paladin spell that would work for you, and flicker is an amazing mystery that works kind of like Travel Devotion in that you set it up, and for next rounds/level you can teleport as an immediate action. All of these are limited and very difficult for you to acquire though.
Sparring Dummy of the Master
This thing requires that you either be a monk, or consistently hit very-high UMD checks. But, it turns your 5 ft. steps into 10 ft. steps, permanently. Very nice on any skirmisher.
It does not auto-adjust.
I agree with John Campbell of the giantitp boards on this one. When the Bone Bow says that it
functions as a composite longbow with regard to applying the user’s Strength bonus to damage done with arrows shot from it. (75)
I see no reason to assume that it only applies to parts of the rules text concerning composite (long)bows and their interactions with the wielders Str bonus.
All composite bows are made with a particular strength rating (that is, each requires a minimum Strength modifier to use with proficiency). If your Strength bonus is less than the strength rating of the composite bow, you can't effectively use it, so you take a -2 penalty on attacks with it. The default composite longbow requires a Strength modifier of +0 or higher to use with proficiency. A composite longbow can be made with a high strength rating to take advantage of an above-average Strength score; this feature allows you to add your Strength bonus to damage, up to the maximum bonus indicated for the bow. Each point of Strength bonus granted by the bow adds 100 gp to its cost.
The only clarity issue here is the pricing of the modifier, which differs between the Longbow and the Shortbow
Each point of Strength bonus granted by the bow adds 75 gp to its cost.
Considering that 100 and 75 gp are the base costs for the composite long- and shortbow respectively, it can be assumed that every point of Str modifier costs the full base price for the bone bow as well, which makes the bone bow quite expensive, especially considering the feat requirement.
Should it?
On the one hand, I'd say it shouldn't, because I can't really justify it in character/in world, and my gut says no.
On the other hand, both (most) archers and exotic weapons are well known to be rather weak in D&D 3.5, even compared to other mortals martials. Giving them a boost (which mileage varies widely depending on how often you Str rating changes) is certainly not game-breaking, especially if they need to burn a feat to use it, on top of those other restrictions.
Best Answer
Adding Dexterity to damage
The Dead Eye feat from Dragon Compendium lets you apply your Dexterity bonus to your damage with ranged attacks. Note the errata for Dragon Compendium that reduces the BAB requirement to +1 (instead of +14!).
The Crossbow Sniper feat from Player’s Handbook II adds half your Dexterity bonus to your damage with crossbow attacks. Crossbows are difficult to use, but this feat can be a decent reason to try. See this answer for more on making the most of crossbows.
The hit-and-run tactics fighter alternate class feature from Drow of the Underdark allows you to add your Dexterity to damage when attacks flat-footed foes. Making foes flat-footed is pretty tricky, but if you were using sneak attack, you were going to have to do that anyway—this is a pretty big bonus on top of sneak attack for doing it.
Increasing your Dexterity
Enhancement bonuses to Dexterity, e.g. from gloves of dexterity, are a high priority for you. You should have the largest enhancement bonus you can afford just as soon as you can afford it.
A racial bonus to Dexterity is less important. Particularly if it means not getting a bonus feat, or taking a penalty to Constitution.
Beyond that, one of the biggest chunks of Dexterity in the game is from the wildrunner’s primal scream, which works kind of like rage. Wildrunner is from Races of the Wild.
Adding something else to damage
Sneak attack, as mentioned, is traditional, though getting foes flat-footed for it is difficult. If you go that route, definitely also grab hit-and-run tactics and the Craven feat from Champions of Ruin.
Knowledge Devotion, also mentioned, is definitely worth grabbing. It’s solid bonuses to attack and damage, and it’s pretty inexpensive.
Hank’s energy bow from the obscure D&D Cartoon DVD’s booklet on the main characters is also reproduced on their website. It effectively gives you Power Attack with your arrows. That can potentially be a pretty serious amount of damage, though sadly you do not get the 2:1 returns that Power Attack does with two-handed weapons.
Adding Charisma to damage is available through a variety of methods, such as the hexbands from Magic Item Compendium, or the Divine Might feat. Notably, Charisma can also replace Dexterity on bow attack rolls via Charming the Arrow, though between the need for Dexterity for archery feats and the various options for adding Dex to damage, I’m not sure it’s worth it.
Along similar lines, but almost-certainly not worth it, swordsages from Tome of Battle can add their Wisdom bonus to damage rolls made as part of strikes made from a chosen discipline. Not many of those strikes are compatible with archery, but if you choose carefully you could maybe do it. You can replace Dexterity with Wisdom on ranged weapon attack rolls with the Zen Archer feat from Complete Warrior.
Getting more attacks
The traditional route to archery damage is just by having a huge number of attacks.
Rapid Shot is the obvious example of this. Manyshot is not, however, as it only lets you apply bonus precision damage to one of the shots and it eliminates any other bonus attacks you might have (e.g. the one from Rapid Shot). Greater Manyshot fixes the precision damage limitation, though you still do not benefit from other bonus attacks.
Beyond those...
The whirling frenzy rage variant can give you another attack.
Haste gives you an extra attack, if someone would be kind enough to cast it on your party (they should, it’s one of the best spells in the game). If not, a speed weapon could suffice.
Speaking of weapon properties, splitting from Champions of Ruin turns every arrow into two. Which means it doubles your attacks, including all the extra ones. It even works with (Greater) Manyshot. It’s a +3-equivalent, but it is so very much worth that.