Gwigle is an online puzzle game that actually teaches you Google search tricks as you play. Each screen shows a few search results along with the search string at the top. One word is replaced with question marks; it's your job to fill it in. It's hands-on education that feels more like you're playing a game than learning useful knowledge.
Glancing at the search results gives you clues as to what the mystery search term is. If you're stuck, you can always hit up Google for some clues. Simply copy some of the text from Gwigle and search away.
Some of the puzzles are a little tricky and it can be difficult to find the answers, even with thorough Google research. Most of them are fairly easy, however, and won't take you too long to complete. You can always bookmark the puzzle you're on and come back to it later.
Gwigle is a great puzzle game for anyone, not just power Googlers-to-be. Give it a try and see if you accidentally learn something useful.
Thanks to Wang for sending this one in!