I have a great yellow cake recipe that gets good reviews but vanilla is so blah...what are some good ways to mix it up? I've tried mixing in some dulce de leche, chocolate chips, crushed oreos, key lime juice...anything else?

I would think any combination of fillings and flavors you can think of.

Check out the gourmet cake flavors thread. I believe it is based mostly on mixes but should still give you some great ideas. It is a huge thread w/lots of links to others