Blogdigger
RSS search engine, providing full-text search, as well as metadata search on RSS information. It has link search funtionality, as well as searching by date, topic, title and other fields.

Daypop
Search thousands of news sites and weblogs from around the world.

Technorati
Searches weblogs by keyword and for links. Also provides news from general news services and blogs.

Feedster
Search engine for RSS feeds, which constantly monitors the world of blogs. Includes an image search.

Ariadne - Weblog Search Engines
Phil Bradley looks at the developments occurring with weblogs and how to go about searching on or for them.

Blogdex Search
Search the Blogdex database for words appearing in a referenced URL, or search for words or phrases appearing in a blog's description.

Popdex
Search allows for finding words in news, referenced links, blog URLs or descriptions and also allows for finding all blogs pointing to a particular link.

Blawg Search
Browse or search law-related blogs in a variety of ways.

BlogDump.com
A search and browsing tool for weblogs. It aggregates search results from leading weblog sites and sources and presents them in an intuitive and easy-to-use interface.

Search 4 Blogs
Categorized browsing, advanced search and the latest 10 additions.

Boogieplay
Searchable aggregation of RSS feeds from various blogs.

PubSub.com
Filter over one million weblogs and information streams to find content you're looking for, in real time.

Postami blog tracking
Search blogs by keyword thoughout the world.

Waypath
Search link references, related books, related posts and web logs and individual web log posts.

Deskfeeds
Search blogs and RSS feeds or browse by category.