i almost forgot i had this sigma 28-80mm zoom. i haven't used it forever, but i didn't sell it off because it's the only lens i have that can do 1:2 macro. but i don't like macro shots; they feel way too easy. so i'm about to loan this lens out, and i figured i would play around with it just to see what i could get out of it. surprise: i had a hell of a lot of fun with it. the 580EX with a sto-fen diffuser makes a pretty versatile lighting tool when you're shooting at such a close range, so i was able to stop down far enough to eliminate most of the defects you'd expect from a cheap consumer zoom. it still has some softness, but it's acceptable. trying to focus manually at f5.6 was almost impossible, but it's a good fun tool to break out of a rut so maybe sometime down the road if i'm feeling stuck i'll pick up canon's 100mm/2.8 macro. it's not terribly expensive as quality lenses go, and it can go up to 1:1 magnification, and it's a prime.
OR, maybe i could save up for the completely DIGRONCULOUS MP-E 65mm/2.8 Macro. it goes all the way up to 5:1. check the sample pics at the review, and also pay attention to how much that lens can extend. it's like a transformer.