C/2006 M4 (Swan)
This was a fairly obscure comet that briefly managed to make magnitude 5 and be visible thru binoculars even from urban St. Louis, MO.
I observed this comet on October 23 and October 24, 2006. The first night I nabbed it from a semi dark-sky site. The forcast was good for the next night, but lousy thereafter. Unfortunately, I needed to take my daughter to a mini-Med school class at Washington University that night. So I was feeling a bit lousy that I wouldn't get the necessary 2nd viewing of this comet.
I couldn't drop her off and get to a nice dark sky site, so I decided to at least try from the other side of Forest Park, near the Planetarium where the St. Louis Astronomical Society often sets up scopes. It was cold and I got my 10x50's out and gave it a desperate try. I was shocked that I actually found it. I suspect it had an outgassing event or otherwise got brighter, lucky for me.
(note: I also observed comet 4P/Faye on the 23rd, but a tail was not seen with any certainty)