Most programs you can just drag to the trash.
There may be support files left behind in Home/Library/Application Support or Home/Library Preferences. You usually can do a search for the program name to find these files...in most cases it will just be a small little preferences file that you don't even have to worry about.
There are some programs (such as the new Safari Beta) that come with an uninstaller. If the program you want to uninstall came with an uninstaller, I'd recommend using that rather than just dragging the app icon to the trash.