ACP Web Services 2.0.0.2 - Search 200+ different search engines. (Free)
ACP Web Services is a group of over 250 search engine services working off 'Services' on your menu bar and includes a service manager app so you can edit them and add new services of your own. (The package includes a tutorial which shows how easy it is to do this.)
Services offered include BugMeNot, all 18 Google URL translation services (including the new Chinese, Japanese, and Korean services), CBL, 5 Dogpile, FreeBSD Darwin, 9 Google (including 'Scholar'), 3 Mamma, Teoma, 6 Vivisimo, 8 Lyrics services, 11 Quotations services, 95 Google international sites, 3 Google Stocks, 8 Web India URL translation services, 6 Yahoo, ARIN Whois, Abuse Whois, Acronym Finder, Amazon US, Amazon UK, British National Corpus, DMOZ, Dictionary, Epicurious, Epinions, Google BSD, Google Linux, Google Mac, Google Microsoft, IMDb, Mac OS X Hints, MacMiner, MacUpdate, Merriam-Webster Dictionary, Merriam-Webster Thesaurus, Mooter, MusicMoz, 3 Mail services, 2 Netcraft services, NetLingo, OneLook, 2 Ping services, PriceGrabber, Thesaurus, Ticketmaster, 3 Traceroute services, VersionTracker (OS X), Visit URL, Whois.Net, Wikipedia, Webster's Rosetta, World Factbook, Wunderground, eBay, wordIQ.