Firefox Help: Keyboard Shortcuts
Microsoft's software is pretty hit or miss (I could live without them), but I like their hardware. I paid $16 or so for a surplus wireless intellimouse 2.0. Version 5.2 of their software lets me map one of the many buttons to kestrokes. This page lets me know what Firefox mappings are available.
Now I use the small side button to send FF a Ctrl-PageDown, and thus to hop around tabs. Works great, but I may try another button.
Intellimouse s/w allows mappings to be application specific too ...