Google has something that searches your site. Or maybe this one. Or did you mean something else? Because you can search your blog using the Blogger bar at the top.
The Blogger site search is terrible -- sometimes it works and sometimes it seems to have no clue, even if I search for a band I've written about several times.
yeah, i barely get any hits from the blogger search. it's always from google or yahoo! search engines - even MSN (some people prefer it - and those are easier to use than the blogger search.
i've never even searched blogger with the search box on the top. ahaha.
I use Google's customizable site-search. If you're an adsense member, you can create a custom site-search that displays your logo and gives you a cut of the ad revenues (ads get displayed either way).