Summary: While this is an older Canon "Prosumer" body, it's actually stronger in image quality than the 50D and a more robust professional body than the 60D. The image quality and low light performance of this camera is great. I would recommend this body to anyone who's advanced past the Rebel line of beginner cameras, but doesn't have the cash to afford a 7D or 5D. The only drawback for this camera vs. the 50D is the lower resolution LCD, but that doesn't effect picture quality.
Summary: The EOS 30D replaced Canon's previous 'winner' the much acclaimed EOS 20D. It has some nice upgrades and although still offering 'only' 8.2 Mpixel produces spectacular prints right up to 16x24 and beyond. Nice upgrades include a colored menu display and larger rear screen LED display in addition to a faster continuous shooting ability. Probably well worth the $100 or so dollars (moore than the 20D) these cameras fetch uswed and of course they tend to be newer!
Summary: The Canon 10D was my first digital SLR. I have always had A soft spot for it. Not only because it was my first but also because it takes great pictures. When you hold the 10D in your hand it feels very rugged and strong. There A perfect choice for someone who wants to seriously get into photography and not spend a ridiculous amount of money. I am writing this on 11/20/2010 and both my 10D's work great and are 10 or more years old.
Summary: I currently own two 1D Mark II's and a 1D but after renting a 5D for an assignment I fell in love with full frame. Unfortunately, I have little spare money. The file the 1DS produces is outstanding. I much prefer the focusing system over the 5D and I like the ease of setup for back button focus. I use the voice recorder a lot so this is another advantage over the 5D.
Summary: I would say if you are getting into photography and want a good camera to start off with, get the Canon 30D. It's easy to use. Don't be fooled by the buttons. Read the manual!!! But basically it's just a matter of technique. It's a solid camera, using a Compact Flash (CF) card. Cleaning it is very simple. And the on screen display, is very easy & comfortable to navigate through. This camera can use the higher L-series line of Canon lenses, too. A huge plus.