Fritz at Cyclelicious has written a script to query Google Blogsearch from a box on your site. You can do this from the navbar if you're on blogspot, but if there's no navbar, or you're not on blogspot, then this is the searchlet for you:

This code is based on the code for the search box in the Blogger.com title bar and uses Google's Blogsearch search engine. JavaScript is usable on any server. The disadvantage is that many people disable JavaScript on their browsers. This code will work for any blog that Google Blogsearch knows about, not just Blogger.com blogs. Note that if you run a blog with Blogger.com and use the Blogger.com title bar, you already have a search box at the top of your blog.

You can get fancy with the interface if you want and search by author, by tag to create a primitive categorization scheme, and so forth.

See Cycle.icio.us for the code, & for instructions on how to make the (minor) customisations that are required.

Filed in: search, blogtech, google, blogger-hacks