As a Mac heathen OSX user for 2 years, there are some apps which makes me don't want to go back to Windows, because there are no similar apps ( or equivalently good version ) of it in Windows.
Here is a list of the best apps that are nice to have, with links to their website and a quick summary:
Moom - "Move and zoom windows".
A better way to organize windows instead of dragging window corners around.
Alternatives: Divvy, Cinch, BetterTouchTool.
Alfred - "An award-winning productivity application for Mac OS X".
Gives you a magic bar that can do tasks for you. Definitely must install.
TotalSpaces - "The ultimate grid spaces manager for your Mac".
A quite powerful spaces (or more commmonly called desktop) manager in OSX.
TotalFinder - "Brings colored labels back to your Finder and more!".
An overall upgrade to the built-in OSX Finder app.
mpv - "A free, open source, and cross-platform media player".
Screw MPlayerX ( it's not bad, but IMO mpv is definitely better ), this is the best media player on OSX; you might have to compile it yourself though.
There are precompiled binaries here, or you can use Homebrew to help you on compiling it.
Homebrew - "The missing package manager for OS X".
Read post #59; don't be afraid of terminals, Linus
Alternatives: Fink, MacPorts.
Entropy - "Powerful Archiver For Mac OS X".
The most bloated fully featured archiver app in OSX.
Little Snitch - "Little Snitch protects your privacy!"
Probably the best firewall software on OSX. Useful for blocking connections and using illegal app copies.
Karabiner - "A powerful and stable keyboard customizer for OS X".
Unbelievably powerful keyboard customizer. Remap every key you want.
iStat Menus - "An advanced Mac system monitor for your menubar".
Shows various system statuses on your menubar.
Bartender - "Organize your menu bar apps".
It took me a while to find this app; it's awesome once you have stuffs cluttering your menu bar.
1Password - "Simple, Convenient Security".
The most expensive An excellent password manager app. Great UI, awesome browser integration.
There are free alternatives available on the internet.
SteerMouse or SmoothMouse
Allows you to disable the annoying mouse acceleration that is hard to disable manually on OSX.
I recommend installing this ASAP before you get used to it.
Textual - "An IRC client created specifically for OS X, designed with simplicity in mind.".
Arguably the best (paid) IRC client on OSX.
Thunderbird
Everyone's best email app forever!
There are lots of email app alternatives. However thunderbird starts to shine once you linked many email accounts into it.
The others seem to be optimized for 1/2 email account(s), unlike Thunderbird, which can still manage dozens of email accounts quite nicely. Cmiiw on this.
Growl - "The Ultimate Notification System for OS X".
Aims to be a replacement of the Notification Center, allows you to modify and control the appearance of notifications.
