To start things off, here’s my menu bar. It’s far too crowded, but I use everything on there:
SugarSync - For syncing/backing up important folders outside of Dropbox.
Dropbox - Because it’s the best syncing service there is.
Sparrow - So I know when I have new email.
/Fluid - A Fluid app for Google Tasks, for easy access to my to do list.
Plex Media Server - So my media is indexed and ready when I open up Plex.
Jumpcut - An essential clipboard manager, especially useful for copying multiple quotes or links.
Time Machine - So I can quickly initiate a backup manually.
iStat Menus Memory and CPU - To see if any programs are misbehaving, with one click access to which ones (there’s a dropdown with more info).
iStat Menus Network - To see my upload and download activity, and also if my Internet connection isn’t working, since it will be grey.
Airport - To quickly connect to Wi-Fi networks (since I use my computer in a lot of different places).
iStat Menus Battery - A more customizable battery display than the system default, with depending on the state, and more details in the dropdown.
Volume - So I can quickly see if my Mac is muted or not.
iStat Menus Calendar/Clock - Another system replacement, since iStat Menus includes a calendar and the time in other cities in the dropdown.
Spotlight - I search my computer often enough.
I occasionally also have Flux running.