alias top = htop
Htop is a top replacement, with colors, per-cpu load indicators, scrolling (specially horizontal scrolling so you can see the whole command line for each process), searching, a nicer interface to kill/renice processes, mouse support, and the ability to call strace/ltrace/lsof easily on the process you want.
alias info = pinfo alias man = pinfo -m
Pinfo is a lynx-style info and man browser. The main reason to use this, IMHO, is that GNU Info simply sucks as a browser. I’m not so sure about replacing man, as I’m confortable with less-style keybindings, but the ability to follow links to related manpages is a great feature :D
Both are included in all popular distros, so installation is only a matter of looking for the packages in the distro repositories.