I think a few companies sell lowering springs. If I remember, Hotchkis and Edelbrock sell them... but I wouldn't waste your money.
If you want lower, go to
http://www.show-n-go.net/gfiles/g_spring.html or jeffd.50megs.com
I picked the 5658 springs, and the car settled around an inch lower than stock. Though, keep in mind, that's a stiffer spring, but you should run a stiffer spring if you're lowering the car, to make it less likely to bottom out.
For the rear, I haven't picked my springs yet, I'm still running stock, but either of those sites should give you a good idea of what spring would work well.
Though, by all means, if you've got too much money, go ahead and blow $300 it on Hotchkis springs, or some other "lowering springs" for your car.
Though, I'd be happy to take your extra money if you sent it to me, I could order the $50 5658 springs and you could pay me $140.
For another $140, I could pick out some $50 rear springs and send them to you too.
The bottom line is, buy OEM springs (preferably American made) from a local parts store rather than getting screwed out of your mind by buying Hotchkis or Edelbrock springs. Many Jap-crap drivers have to buy expensive springs simply because there aren't OEM type springs that fit their application, but lucky for us, we have the S-10, A-bodies, G-body wagons and F-bodies.
BTW... I've had a harder time with quick 60' times now that I've stiffened up my suspension, and I've only done the front end!