This is a pretty basic tip, but if you don't know it, it's VERY handy.
In Internet Explorer, type in the domain name on the address bar, without the www. or .com.  If you then press Ctrl + Enter instead of just Enter (or clicking the Go button), IE will automatically add the www. and .com.

Those nanoseconds you save with this tip will surely add several minutes to your life.  What will you ever do with that kind of time.