RealBASIC 2007R3 is by far the best development tool I've seen out there (yes, even better than Xcode). Why do I say that? For a simple reason: it's cross-platform. On my MacBook I created a simple history quiz in about 20 minutes with a Visual Basic-like language that ran on my Mac and my PC running Windows XP and Ubuntu Feisty.
One problem with this easy cross-platform IDE is that you have to be careful about designing your interface. My program's interface worked fine with OS X Tiger and XP, but with Ubuntu, things got a little weird. Some lines were too long, cutting out part of the text, and the "Submit" button I put was halfway cut (you can download this quiz, by the way at http://code.google.com/p/studyquiz )
System requirements aren't too bad. Windows 2000/OS X Panther or later, 1 GHz processor/ 1 Gig of RAM. Compiled apps run on systems as old as Windows 98. The pricing of the product, however, is pretty high. For standard, you can pay $99. If you want your apps to be cross-platform, $500 is the price you pay. You can by RealBASIC at realsoftware.com/store.
I give RealBASIC 4.5 apples out of 5, losing an apple for a ridiculously high price.