How can I get my Mic working under Debian GNOME?

"If you're lucky, it's just feedback from the mic setting being so sensitive that it's picking up the output of the speakers. To make sure it's not this, plug in some headphones and listen to them when you turn the mic on.

If it's not that - I remember having a similar problem a while back and it turned out the driver for my soundcard needed upgrading (otherwise they locked up when accessing the mic). Without knowing your sound card, it's hard to say where to find such an upgrade, but what version of Debian are you running?"