Flash Drives won't show up

Hey,
Im running an MBP with OSX Lion.
Whenever I plug in a USB Flash Drive, it shows up in Disk Utility as mounted and I can Erase/Format/Verify them etc. but it won't show up in the left sidebar in finder or the desktop.

i.e. I have no way to access the drive.

What gives?
They were working fine earlier. This is a new problem.

Open a Finder window and open Finder Settings from the menu bar (Finder -> Settings). From there navigate to Sidebar and make sure that External Disks (under Devices) is selected. The actual names might be a bit different as I am using the german client.