Normally in Bash the up/down arrows will cycle through your most recent commands. This is all well and good, but sometimes the command you’re looking for is not in your recent history and you need to go searching for it. It would be nice if, for example, you could type ss, hit the up arrow, and have your most recent ssh command appear, even if it’s buried somewhere in your command history.
If this interests you, put the following in your .bashrc file:
bind '"\e[A":history-search-backward' bind '"\e[B":history-search-forward'
This binds the up/down arrow keys to search through your history rather than your most recent commands — in other words, it’s like an autocomplete for your history. Bash doesn’t save your entire history, so it won’t search through every command you ever typed, only the most recent ones.
Some other helpful terminal things I found:
Ctrl+c: delete the current command and get a fresh prompt
Ctrl+e: move cursor to the end of the current command
Ctrl+a: move cursor to the beginning of the current command
Your mileage may vary, but I think these things are pretty useful.
Edit: People seem to recommend adding the following two commands below the key bindings in your .bashrc:
set show-all-if-ambiguous on set completion-ignore-case on
…although I have yet to figure out when and whether this is helpful.