www.webtender.com
You can input the liquor you have and it'll give you a list of drinks you can make with it.
I always do white russians. They're pretty much impossible to mess up, too.
If you do Cherry UV Vodka and Vanilla coke, blend it with ice, it tastes just like a slushie.
Umm... You mentioned the screwdrivers, but there's also sloe-screws, comfortable-screws, japanese-screws, screws-against-the-wall- all of which are screw drivers which add sloe gin, southern comfort, midori, or galliano, respectively.
Grasshopper is something like vodka, green creme de menthe, white creme de cacao and whipping cream- chilled and shaken till thick and frothy.
Snakebite shot, if I remember right, is Yukon Jack and whisky.
Nobody's mentioned an Audios Motherfucker yet, which is a LIT but with blue curaco instead of triple sec and topped with 151...
I used to know a lot of cocktails that sounded good, but I forgot most of them 'cause i never had the money to actually try them. If I remember more, I'll post them. =\