Andus Purde over on Skype for Mac blog makes some excellent brief points on which webcams you can Skype with on your Mac. As Andrus observes, "Apple iSight, Philips SPC900NC and Logitech QuickCam Pro 4000 are pretty safe bets", but there really are quite different cams you can use for your Mac.

A couple of other points from Andrus:

• Many other cams can be made to work with Skype on a Mac by downloading a suitable driver from http://webcam-osx.sourceforge.net. List of cams here.
• Make sure you have at least an 800Mhz processor to run video on your Mac
• Ensure you don't have more than one video window open at any one time, as the cam can only communicate with one application at a time
• Check out the knowledgebase or look at the forums for more information if you're unsure about a particular webcam's compatibility.

Also worth summarising a few points from the extensive comments Andrus' post drew from users:

• Some users seem to have got the Logitech Quickcam Pro 5000 working with their Mac, despite it being officially listed as not Mac compatible. However, some users not so successful
• Lots of positive comments on Ecamm's iMage Webcam
• OS X 10.4.9 seems to have fixed a few problems with cams not working
• Reports of Logitech QuickCam Ultra Vision working out of the box with the Dual Core Mac Mini
• Logitech QuickCam Messenger reported OK on one user's Powermac G4 1.25Ghz
• One user reporting problems getting the Logitech Communicate STX to work on Mac Mini, 2 others reporting picture OK but no sound
• A couple of Macsters thinking outside the box have rigged up their MiniDV camcorders via a digital/analogue converter and are using those as webcams. Not pretty, but hey if it works!

Obviously none of the above offers firm guarantees on what works/doesn't work, and it's usually best to go along with the compatibility stated on the product description, but Andrus' article is a good place to start for any Mac Skypers with webcam aspriations...