Firefox has a neat feature called Smart Keywords that allows you to quickly search databases from your address bar. Let's say I want quick access to RootsWeb Town Search. I right-click in the "Town Name" search field, and select Add a Keyword for this Search from the menu that appears.
One drawback for genealogists is that Smart Keywords accepts only one search term. Most of our searches require two or more fields with distinct values (e.g. first and last name). But there are many sites I use regularly where this method does come in handy, including Google Book Search and News Archive Search.