If you like watching what the world is searching for, search spies (programs that output the searches that are being performed on the site in real time) are a fun resource. Over at SEOChat, Mick's asked the question and Jammer & Skipsel have provided very nice lists. There's quite a few:

• UK Sprite
• Dogpile (unfiltered & filtered)
• Excite (also filtered & unfiltered)
• Infotiger (never heard of them)
• Search Engine in the Netherlands - top searches from past 30 days
• Ilectric
• Fireball (auf Deutsch)
• Zoekspion (Netherlands)
• Kobala (more from the Dutch)
• Splat Search (random queries)
• WebCrawler
• Jeeves IQ (Interesting Queries)
• http://hot.aol.com/hot/hot (Hot at AOL)
• Metacrawler (filtered and unfiltered)
• Search.com (top 1000)
• Ozsearch (Internet Guide)
• Dip Box
• Abacho (in German)
• Verizon

Great list, guys. A scraper could sure have fun with this.