If you drop down the "Location" (or "Address" in Internet Explorer) drop-down list box, you'll see a list of locations you've been to by typing their URLs.
Here's how to get rid of those typed URLs from the history:
Exit Netscape Navigator or Internet Explorer
Run "Registry Editor" (run "regedit.exe" or "regedt32.exe")
If you're using Navigator 2.x or Navigator 3.x, select:
HKEY_CURRENT_USER\
Software\Netscape\Netscape Navigator\
URL History