I don't know how many of you have seen this, but it's quite interesting. This guy gives code and a full mod that adds bump mapping int HL1!! It's pretty cool, check it out. Been out a couple of years so I'm sure u veterans like the monkeys, hunter, unbreakable, orph, muzzle and COUNTLESS others who are always on these forums have seen.
http://collective.valve-erc.com/index.php?doc=1091469531-97736200