My 10 favorite apps for the Mac:
2. Airfoil/Airfoil Speakers - If you own an iOS device or Airplay devices this is a multipurpose app that allows you to send any audio to Airplay devices and the "Speakers" part of the program will allow you accept an Airplay signal from an iOS device (great if you prefer your Mac's speakers to your IOS device speakers).
3. Crashplan - This will backup your data to the cloud.
4. Splashtop Personal - Easy way to access your Mac from anywhere (including iPads and iPhones).
5. BitPerfect - There are some great audio apps for the Mac, but BitPerfect is only $9.99 and works with iTunes. One great feature is automatic sample rate switching. For example, when you play a 24/96 file in iTunes, it will output it at the default sample rate that you are using (typically 16/44.1). You can change it in Audio Midi manually, but this app handles that process automatically.
6. Evernote - This allows you to save lists, clip web articles, and more. It will sync across many different devices, so it is also one of the best apps for iOS.
7. Pocket - Personally, I use this to gather articles from the web and apps like FlipBoard (iOS) and when I see something I want to keep or add to a list, I save it to Evernote. Using the two together is a great way to streamline projects in Evernote without cluttering it with everything.
8. LastPass - There are at least 3 really great password managers out there and you should use one of them. I chose LastPass a long time ago when I was still exclusively on Windows, but since it is web based, I was able to move it to the Mac and iOS seamlessly. A lot of people on Macs prefer 1Password, so if you are just starting with password managers, I would review them to see which fits your needs best. Leo Leporte and Steve Gibson like LastPass, so that is one of the main reasons I have stuck with them.
9. Dropbox - Integration into the OS X is seamless. For me, it is still the easiest way to transfer files from a mobile device to my Macs.
10. Hazel by Noodlesoft - I am still in the test phase of this app, but it is simply fantastic. It will look at folders, delete duplicates, automatically empty the trash, move files based on your criteria, etc. I plan to devote an article to it after I use it for a while.
I want to mention that one of my most used applications on the Mac is Lightroom and I would highly recommend it if you are a photographer, but I wouldn't say it is needed for everybody. Also, Apple is getting ready to make some major changes to Photo software, so it may be best for the casual photographer to wait it out to see if it does what they need.
These are definitely some of the best apps for Mac, but of course, the list can't include every single app I like. If I missed an app you would have in your top ten, let me know.