Let the hive mind of Engadget get that for you.
"I've found myself using my PC for a lot of conversations lately, and I'm also considering recording a podcast to share with anyone who will listen. There are tons of USB headset / microphones out there, and I'm hoping someone has some solid recommendations based on experience. I'll consider both headsets and standalone mics, by the way, but I'd like to keep the bill under $100 if possible. Help!"
Standby/Power-off Cell-phone Detection (Looking for Co-operation)
1. RF contact-less detection
2. Portable operation
3. Detection range: 1m ~ 5m, adjustable
4. Cell-phone in transmission working mode / receiving standby mode / power-off mode can be effectively detected
5. Suitable for all restrict area of prohibited cell-phone usage
6. Finish prototype fabrication & performance evaluation