do you mean in the top menu that's usually above the blog entries?
I don't know about Bulletproof and it's unique plugins but you could take a look at this website to get some nice example code for different CSS menus. It shouldn't be too hard to adapt that into the serendipity layout when you know a little on how to edit the files. At least it wasn't with the default template I worked with before.
Doei,
eni
Sorry, I'm Late. But I Got Lost On The Road Of Life.