The splines on my bottom bracket cassette are stripped. How can I get it out of the bottom bracket? Oh, and I don't care about saving the the old hardware.

Are both ends stripped? If you can remove the R hand cup, you should be able to remove the bottom bracket as you remove that cup, leaving more room to deal with the L side. Then, you might be able to grab it with a vice grip or something. If it's plastic, shouldn't be hard to get out. If the R side is stripped, then that's not so simple. Can you get at it with a nail set and a hammer?