Here are some of the apps I use frequently.

Productivity

• LittleSnapper is my favorite screen capture app. Like many similar apps, it stores a library of your captures and has hot keys for common use cases.
• Things is a todo app from Cultured Code. It’s a little expensive (you have to purchase the desktop, iPhone and iPad apps separately), but it adds the right amount of structure without getting in the way.
• Soulver is a tape-based calculator with the edit-ability of a spreadsheet. Watch the video before you put your $ down. If you find yourself making a lot of calculations for a project and you want to see them all at once – Soulver might be exactly what you want.
• DropBox is great for sharing files with other people, other computers and even your iPhone.
• I use Acorn for image editing (including creating the image at the top of this post). I like it, but I know some prefer Pixelmator and others, Photoshop. They are all great options.
• Fantastical sits in your menu bar, showing today’s date. Click on it to get fast, interactive access to your iCal calendar. I use it most for it’s large, drop down month view.

Utilities

• Boom at http://www.globaldelight.com/boom/index.html is a fantastic utility that nearly doubles the volume of your MacBook. It’s incredible for listening to podcasts, music and video when the sounds is just a little to quiet. A recent software update fixed my only concern with Boom – it no longer crashes.
• I prefer VMWare Fusion over Parallels for running Windows apps on my Mac. Historically, it eats less battery life, in my experience.
• iStat Menus puts CPU utilization, memory usage and other computer-health metrics in your menu bar, along with a very nice calendar.
• Stock Menulet shows one or more stock prices in your menu bar.
• Hyperdock emulates some of Windows 7’s best features. Drag a window to the side of your screen and it will snap-resize to fill exactly half of your desktop. Move your mouse over an app’s icon in the dock to see a preview of the windows owned by that app.
• DaisyDisk: if your hard drive fills up quickly and you find yourself cleaning out media files or downloads frequently, DaisyDisk can help. Like many other tools, it helps you visualize where all your space is going, but it’s much more fun to use than its cousins.

Development

• xScope provides awesome tools for measuring distances and areas on screen. Magnifying glass, guide lines, etc. I use this a lot.
• Hues replaces your color picker with something much more useful. Save more custom colors, work with more color formats – it even has better copy/paste and an eye dropper!
• Transmit is great for FTP, S3, etc.
• iTerm 2 is a great replacement for the built-in Terminal. Split panes, colored output, scriptability. Good stuff!