You can't develope your apps without some sort of development environment. Here is a list of resources for development tools.
Platforms: Android, Windows, Apple
Hands down simply the best and easiest tool out there. Create your first app in minutes. Tools and libraries for everything from games to
maps to social apps. No comparison. The fastest way to to your app developer dreams.
The Game Creators
Platforms: Android, Windows
Another awesome tool. Geared towards games with a bit more of a learning curve. TGC has been arounf for a while and has one of the largest user base with
a forum that has no equall. If gaming is your game then check out TGC.
A relative newcommer to the app developement game but still worth a look.
Another robust tool worth taking a look at. Claiming to have "the world's most advanced development platform", Corona Labs is
definitly a contender. There is, however a monthy fee.
Java - Platforms: Android, Windows, BlackBerry
For experienced programmers. There is simply nothing you can't do with Eclipse. It's also free. The learning curve is, well, large.
Also, there is lots of web support for Eclipse. Google has extensive documentation supporting direct Java programming.
If you are an experienced programmer/developer then chances are you already use Eclipse. However, if you are a newbie to programming and want to
jump right in then we recommend
Anywhere Software. You will be up and going in no time.
Platforms: Apple iOS
If your developing for iPhone or iOS then Xcode is where it's at.
Platforms: Windows Mobile