This instructable describes how to mount a VU meter into a case of an old cd-rom drive and then put it into your pc. On eBay I bought a bunch of VU meters based on VFD displays build in Russia. The displays where rather cheap and looked nice. I thought I'd give it a try. When the vu meters arrived I realized that on all devices there was one transistor missing. To make them work again you need to "repair" the vu meter ... don't panic you can easily solder a substitute transistor onto the pcb.
http://www.instructables.com/id/Building-a-VU-meter-for-you-multimedia-PC/