Session saving in Firefox through the Tab Mix Plus extension. Saved my bacon on a number of occasions.
iStats menus. The menu bar items are cool, as well as the iStat pro Dashboard widgets. Reminds me that I need to make a donation.
DyDNS.com’s MailHop Outbound SMTP service. Pay $15/year, get 150 outbound messages a day. Beats the heck out of keeping your own SMTP relay up, running, not busted into and not blacklisted. Also supports working around stupid firewalls you see in many travel settings.
Dashboard in Mac OS X. Oddly enough, I decreased the clock size in the menubar and now I use Dashboard more frequently to check the time. This is making me appreciate Dashboard’s utility.
Search templates in LaunchBar, although I need to break the muscle memory of doing a Google search through the Firefox URL field.