There is also a DuckDuckGo hidden service at 3g2upl4pq6kufc4m.onion for Tor users.
MetaGer is a SaaS by the German non-profit SUMA e.V. that provides you with anonymous meta search results.
Startpage is a SaaS hosted in the USA and the Netherlands that provides you with anonymous Google search and image results through a free proxy.
Ixquick (run by the same company as Startpage) is a meta search engine that returns combined results from nearly 100 sources - excluding Google.
Seeks acts as a personalizing Web server or proxy between you and your data feeds. Connect most search engines, RSS/ATOM feeds, Twitter/Identica, Youtube/Dailymotion, wikis, and basically any source of data, and Seeks will produce a fused personalized stream of results to your queries. See list of Web Seeks nodes.
Tor users may use Seeks hidden service at 5plvrsgydwy2sgce.onion.
YaCy is a promising project that offers fully decentralized peer-to-peer search. The more people who start using it, the better the results will become.