I got an email from a someone last week (I wont reveal his name as I didn't ask him if it is OK to mention it here) who said he had found an interesting link whilst looking for something else and he thought I would find its contents interesting. The link is "Welcome to ITEC's Orasnap reports". This page has a lot of links to detailed reports generated by some tool called OraSnap v3.0.0 that reveals a lot of details about a lot of databases. An example is here.
Whilst it might not be possible for a hacker to access to these databases, some of the information is recent and detailed. The person who sent me this link said I should take a look as its interesting to see the details some sites reveal. The message here is check what your own websites reveal about your own Oracle installations. Don't send out a calling card inviting hackers to come in.