Take a look at the factory_girl_sequences gem, which provides a basic set of the most common sequences.
In simple projects without a complex business logic, you just need a set of simple sequences to generate fake data. This can be a login, password or IP address. The idea to write this mini gem came to me when I, again, was looking for a sequence to generate the IP address. Of course, I could write it from scratch, but I’m a bit lazy :)
In any case, check out the project page on GitHub.