When I upgraded to Ubuntu 12.10 I noticed spell check no longer worked in Firefox or Chromium. I seen a million threads on how to fix it in Firefox (See it here), so its working in that browser, but still not working at all in Chromium.

Then after some messing around, I got it to work. All I had to do was right click in a text field, go down to spell checker options, then uncheck "ask Google for suggestions". After that, it started working just fine. (You may have to reboot Chromium for it to take effect.)