Use Google for any kind of hash searches. Its the fastest method to get results, and if it isn't in bitzi, hash information may be published on other sites.

To manually search via Bitzi, you can start here: "http://bitzi.com/lookup/*" though even here, it'd be faster with Google if you do a search using "Base32 SHA1 hash begins with" bitzi AAA, where AAA is the first three characters of the hash.