Not Tmux, but one of my favourite things about iTerm2 is the search/copy functionality from the keyboard. I often find myself reaching for it, for example

git log - see a commitish I want to fixup cmd-f type first few letters hit tab to get to the end of the commitish cmd-c esc cmd-v to paste it

The other great thing is when you have cmd-f going and there are multiple hits in your terminal, hitting enter cycles you through them backwards.