Bruteforce Module Features?

I've started making a bruteforce module in python. I was wondering what features you guys would like to see in something like that. So far I have the basics like a dictionary based attack and a whole keyspace attack. What else should I add?

Note: This isn't designed to be a separate tool for password cracking because tools like this already exist. This is a tool to build python programs on.

Thanks
Robyn