HashDB is a networked md5 hash comparison tool that allows you to automatically check the hashes of any files you download against a master database stored at www.immunitysec.com. This allows you to download source tarballs without worrying that they've been replaced by trojaned ./configure files.
4a1fc0b4fd64f1f50f53b470729606f6873f9dff312ef2a66c32af02f31e6501