I am making a 4 tier cake. I have 3 fillings which are basic butter cream, chocolate mousse, strawberry mousse. I need one more to have different flavors. Any suggestions.
Thanks.

what kind of cake is it? sounds like vanilla?
heres a few ideas
lemon mousse
peanut butter buttercream
cookies and cream
white chocolate
raspberry
mint choc
lemon curd
cheesecake
coconut/coconut almond
espresso
hazelnut chocolate (nutella and buttercream)
marshmallow (marshmallow fluff and buttercream, or candy flavor added to buttercream)
mocha fudge and toffee bits
rootbeer (use candy oil)
maple

i found a thread you might want to look at, it has hundreds of flavor combos, i love it!

http://cakecentral.com/modules.php?name=Forums&file=viewtopic&t=614554&postdays=0&postorder=asc&&start=0
hth