BuddyPress.org

I had done it for one of my premium themes and I am in the process of publishing a tutorial too(Still incomplete). It is simple and can be achieved via theme itself, no plugin is required. No mod to your theme(other than adding a blank template file with a do action).
Let me know if you guys want, I will put the code on the pastabin.
Btw, My solutions hooks on the top of bp-functions, so there is no need to create a form(It will just take the bp form and hide the drop down),