In no particular order or context. No personal stuff and by no means a complete list:
WordPress (like, duh).
Wikipedia (default for looking up new stuff)
Wikis in general (great lab management tool. Don’t need LIMS)
FLOSS licensing (90% of the software I use, and 100% of what I write)
Science Bloggers (too numerous to link)
BLAST (Sometimes it feels like bioinformatics is should be renamed to blastology)
LaTeX (Wrote my dissertation in LaTeX, and never looked back)
OpenOffice.org (because not everyone uses LaTeX).
CiteULike (Keeping my reference library up to date and in good order)
Delicious (Keeping my bookmarks up to date and in good order)
Gmail (because finding that document you sent me a month ago would be impossible otherwise)
Google Scholar (For standing on the toes of Hobbits. Or something like that)
GIS (for blogging and making class slides)
Vim (because emacs blows)
Python (ease & power)
Biopython (OK, conflict of interest here, since I contributed a bit)
Friendly colleagues (They certainly are!)
Good students (gotta make my lab page).
Goulash for dinner. Can’t stand oven Turkey.
Music. Especially the latest song that is going around in my head: