There are litteraly hundereds of top 10 app lists for the mac and they are all different. It’s really a matter of how you use your computer and what you are looking to do that determines what your must have apps are. CheapMacApps.com has put together a pretty good list of their own that covers a wide variety of apps. Their list includes:

• RapidWeaver – Creates websites from blogs, photo albums, or just plain HTML pages quickly and easily.
• iClip – Customizable clipboard functionality
• Virture Desktops – Allows you to have multiple virtual desktops on your Mac.
• AppZapper – Application Uninstaller
• Plaxo – online address book services
• Yep – iPhoto like app for organizing your PDF files
• OmniGraffle – flow chart application
• pzizz – creates a powernap soundtrack for relaxation
• Stellarium – view actual images of the skies and constellations from around the world.
• xTorrent – P2P application

Overall its a pretty good list and offers some up some new applications that I hadn’t ever heard of before. Check out CheapMacApps.com for a more complete description of each of these apps and their price, if they have one.