edit: I have posted a web page with these same instructions.
See Uninstalling Apps on Mac OS X.
Yup, it's really THAT simple.
Mac OS X differs from Windows in how applications work on a couple of levels.
For one, Mac OS X doesn't have a registry. There's nothing even closely analogous to it. Applications do not have to register their location or anything like that to work. Application settings and preferences are stored individually per app as "Property List" files in the user's Library/Preferences folder. Sometimes apps may keep additional support files in the user's Library folder, but these are completely inert. They are only accessed by the parent app itself.
Second, Mac OS X apps are almost *always* stored in what Apple calls "bundles" or "packages". The user never sees any more to the app than just the icon itself (unless he intentionally starts digging around for info). That icon for the application is actually a special type of folder, but the system treats it as a single whole application. Inside that bundle icon, applications store everything from the executable code to graphics, sounds, icons, interface files, multiple language support files, and any additional resources the app may need. This eliminated the confusion and danger of storing other essential data files that are part of the app anywhere else on the drive. Now, everything the app needs to run is tucked nicely away within the app's icon itself.
(If you're curious about this, take any app like iTunes or Safari, control-click or right-click it, and choose Show Package Contents. Feel free to peek around in the app. Just be sure not to change anything unless you know what you're doing!)
The best way I have found of explaining the difference between uninstalling apps on a Mac versus on Windows is by showing how to uninstall Internet Explorer from a Mac. Here's a video detailing the process:http://brad.project-think.com/movies/uninstalling.mov
Try doing that
with IE on a Windows machine.
The only things an app may leave behind after you've trashed it are its preferences and support files in one of the Library folders. However, as I mentioned above, this will not
impact your system's performance with the exception of taking up a small bit of hard drive space. These files are inert
and will not affect other programs or the system software itself. In the top-level Library are support files that would affect all users. In your home Library folder are the support files that affect only your user.
In the Library's Preferences folder is where most apps will stick their single preference file. The names of these files may be intimidating at first, but they're all logically done. An example:
The first part is like an internet address's ".com"; this example is from a business. Other common ones are org and country codes like uk or de. The second part is the software maker's name. The third is the software's title. The fourth is the filename extension, showing that this is a "Property List" file.
I usually leave any Library files where they are in case I ever decide to reinstall that program. Keeping them does no harm to the system and gives me the added benefit that the program will remember its settings if I reinstall later.
So, in summary: No registry mess, no "dll hell", no hidden files strewn across your drive. Just drag to the trash and be done with it.