The software has a feature called 'autotype' which I have been aware of for a long while - when you select a log-in, it switches to the immediately previous window, types the user-name, tabs, types the password, and presses 'enter' (so to speak - it fakes keystrokes). This is pretty useful.
When I accidentally hit ALT+A at the same time in Firefox, it suddenly autotyped my password - for the current site. In Keepass, you enter the URL of the site, and can click the URL to open the site, but it turns out that when you are in a text box and trigger this 'autotype' feature it reads the current URL, selects the appropriate login details, and autotypes them. All magically in the background.
That is the coolest feature ever, and will save me absurd amounts of time. Hurrah for Keepass. I can not recommend this software enough (the 1.x series - not the 2.x alpha series).