If you're using a crop camera, which you seem to be, I can recommend canon's EF-S 60mm f/2.8 (effectively a 96mm macro) very highly. It's cheaper than the 100mm, it was designed for the crop format, and although you do lose some working distance (but not very much, I have to say) it's more than made up for by the fact that it works as an absolutely beautiful, and razor sharp, portrait lens.
There's links to quite a few pictures it took with a 30D in my signature. The lessened working distance has never stopped me from getting close to living subjects. I can only think of two problems with it: one real problem (which is that it tends to hunt and never settle in low light, which you can work around) and one potential problem (it's EF-S, so you'll never use it with a full frame camera should you decide to upgrade).
The bee was a throwaway shot just seeing what the lens could do, hence taken on f/2.8 with no real regard to focus (apologies if image posting is frowned upon in this forum; I'm fairly new here). The web I tried a bit harder for, and I was pleased with the result.
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