Beyond thrown weapons, there needs to be a clear niche for heavy/light crossbows and long/short bows. Based on some quick research, it appears that crossbows have far more draw strength, and hence damage potential, than bows, and are easier to master. The main advantage of bows is their comparatively huge rate of fire in the right hands - an expert longbowman could get off a shot every five to ten seconds, whereas a crossbow takes at least half a minute to reload. In medieval times, crossbows were often considered to be "unsporting" weapons used by unruly commoners, to the degree that the church attempted to ban them. Longbows, when they emerged, had nearly equal power and much greater rate of fire, but required far more training.
To represent these differences - crossbows are better unless you are really good at bows - I suggest introducing the following rule: Much as Fighters currently gain an extra attack at the 15th, 20th, and 25th level, Fighters and Elves now gain an extra shot per round when wielding a shortbow or longbow at the 4th, 10th and 18th level.
Also, given the skill and strength required to wield a longbow, only Fighters and Elves may use this weapon in the first place. Halflings can't use heavy crossbows out of size considerations, and Clerics can't use any sharp projectiles, restricting them to bullets, rocks, oil - and holy water, of course.
Based on these thoughts, here's a suggested table with tweaked weights and ranges. (Turns out that bows' effective ranges are also much greater than LL suggests, so I've gently raised them - not really far enough for fear of unbalancing the game.) Comments and suggestions are as always very welcome.
|Hv Crossbow||1d8||10||40||50||100||300||DEF MT||4|
|Spear, thrown||1d8||4||5||20||40||120||DEF MT||2|