I was looking to install the Chromium web browser and installed the chromium-bsu package at the suggestion of the package manager:

mike@mikebox:~$ sudo apt-get install chromium
...
Package chromium is not available, but is referred to by another package.
...
However the following packages replace it:
  chromium-bsu

All the most important discoveries were made by accident: penicillin, teflon, coke, and what turned out to be a very fun space-shooter game.

About an hour of clicking later - back to work. Installing the wrong package is a real time sink!