This is a web site that allows users to do reverse MD5 Hash look ups in order to try and crack them. The database for the site contains over 170 million pre-computed hashes that can be searched in under a second.
More info from the site:
Message Digest Algorithm 5, commonly referred to as MD5, is the internet standard in security applications. The algorithm yields a hash consisting of a 32 digit hexadecimal number, allowing for 2^128 unique outputs. There is no way to decrypt an MD5 hash. While there is no way to decrypt an MD5 hash, they can be cracked. An attacker may use a brute force method in an attempt to crack a hash. Brute forcing is when the attacker puts all imaginable combinations of characters through the algorithm and checks the outputs. When an output is generated with the same hash as the original, the attack is finished and the attacker has cracked the hash. NetMD5Crack offers another way for security analyzers to decrypt hashes. We have compiled a database of over 170,000,000 hashes and their plain text. To use our service simply enter a hash into our FREE MD5 cracker. Our database will be searched thereafter. If we have the hash in our database then the plain text will be returned, saving you hours of time executing brute force attacks.
If the site does decrypt your hashes, google salting MD5 hashes. This is a method to help protect your sensitive data. I would provide you all with a link, but for some reason this forum doesn't like links in their threads.
Hope this is a decent first post