Not sure if it's my best, but definitely my favorite:
Fly portrait by Michael Stoop, on Flickr
Took this shot when I was stalking bees in my backyard on a cold-ish morning. Not cold enough since I didn't get too many of them properly.
However, when I turned back I noticed this guy sitting on the outside of my living room window. It took me about 4 shots to get as close as I did and he still didn't fly away.
Note: Click for the bigger version on flickr for that moiré to disappear. I have no idea how or if I can prevent small previews to get this amount of moiré, but it's not so noticable in the larger version.
Equipment: Canon 40D, Canon 100mm macro with 36mm tube. Manual flash (Nikon SB-28DX triggered with Cactus v4 radiotriggers) with lumiquest mini softbox on manfrotto 330B flash bracket. I thing the focus ring of the lens was right up against the glass on this one.