jQuery pop is a simple little plugin that lets you put an up/down arrow anywhere on your page and when clicked it shows some content in a dropdown div. Handy for those times when you need a mini "menu" effect for a single item, but don't want all the overhead of a menu plugin (and don't need fly-out submenu's).

http://pop.seaofclouds.com/

I haven't actually used this one yet, but got it queued up for a little spin.