Where can I sell things for bitcoins? I have old items that I want to sell for bitcoins. This includes digital content and physical objects.

What websites can I use to sell them?
You can find an extensive list on page Trade at Bitcoin Wiki.

A short list of some auction sites that use Bitcoins:


Bid Bitcoins
Bidding Pond
Bitmit


If you want to sell digital files per download, go here: http://bitcoinservice.co.uk/ .

And as with anything, you can just post on an online classified ad websites, such as craigslist (thanks Thilo for the suggestion).