Hamish & Andy - The 2 best media entertainers currently in the game.

Nerdzilla - Nerd news and flame wars. Only found it a few months ago but it's great. Highly recommended.

Astronomy Cast - If you like the universe and the science behind it, listen to this.

Nightlife - The most interesting show on ABC radio (next is Conversations). The only problem is it's on at 10:00 weeknights so I listen to the podcast instead.