If you have recently switched to an Intel Mac, you may have noticed that your favorite BitTorrent client, Azureus, does not work. Luckily, the Azureus wiki has a special build of the current version, 2.4.0.2, modified to work as a Universal Binary. Until there is an official UB for Azureus, this seems to work great. Download it directly. Hat tip to Felipe for the link.
Update: The download link no longer works. You might be able to find a UB version at GetAzureus.com soon, otherwise keep trying that link.
Update 2: Working download link thanks to Andrei's comment.