Here's a simple recipe for my Mom's Banana Sour Cream Cake. You can frost it with vanilla buttercream, or mocha, coffee or peanut butter buttercream frostings are also great with this cake.
http://dinneratsheilas.com/post/8265837422/moms-banana-sour-cream-cake

This one from FOOD52 user Giulia Melucci is easy and delicious: http://bit.ly/wa4U3V

Rose Levy Beranbaum's Cordon Rose Banana Cake (from The Cake Bible) is pretty delicious. If you add a chocolate glaze or choc sour cream frosting, even better - but good as is: http://www.tastebook.com/recipes/629772-Cordon-Rose-Banana-Cake