My favorite is Ctrl+r for 'reverse-i-search', where you can type in any part of a previous command, and the shell will look it up for you.

That alone is enough reason to install bash (to me at least). The keyboard on N900 isn't bad, but it's not great for shell bashing. Being able to easily find that difficult-to-type line is nice.

Auto-completion on remote paths is also fun, it works if you are using public keys with ssh.