If only finding focus were so simple. With a tidal wave of information coming at us daily, focus is rapidly becoming the scarcest commodity of the 21st century. With this in mind, I’ve rounded up a handful of the best apps for fighting back against the constant distractions of our digital lives.

1. Self-Control – Block out distracting websites for a set amount of time.

If you find yourself slipping into a Twitter sinkhole when you should be updating your business plan, Self-Control may be the app you need. Set it for 4 hours, for instance, and your browser will behave as if it's offline for that period of time. No amount of browser restarts or computer reboots will stop it. Before you have heart palpitations, know that you can whitelist or blacklist certain sites. So, rather than completely disabling the entire Internet, you can selectively decide which sites are OK, or not OK, to visit during your focus period. For Macs only. PC users can try Freedom, a similar app.

2. TrackTime – Audit how you’re spending your time on your computer.

This good-looking app tracks everything you do on your computer, spitting back out a sort of "attention audit." How much time are you spending in Firefox? How many hours a day in your email client? What are listening to on iTunes? If you let TrackTime run in the background, it builds these patterns into a lovely rainbow-colored timeline of your online life. Its most effective use is as a sort of  wake-up call: If your daily timeline shows you shifting between apps and tasks every 2 minutes or less, you know there’s a problem. For Macs only.

3. Concentrate – Maximize focus while shifting between different tasks.

Concentrate is great for shifting between tasks that require different mindsets. I have a variety of recurring tasks that require different tools: 1) Writing, 2) Social Media Management, 3) Event Planning. Concentrate lets me configure a different set of tools for each task. When I activate "Writing," the app automatically closes my email client and Internet Browser; blocks me from Twitter, Facebook, and YouTube; launches Microsoft Word; and sets my instant messaging status to "away". Then, when I want to concentrate on "Social Media Management," I can customize a completely different set of actions to happen relevant to that activity. There’s also a handy "concentration" timer. For Macs only.

4. Notational Velocity – Centralize and sync all of your scattered notes.

If you’re anything like me, one primarily challenge for focusing is getting all your notes in one place. Before Notational Velocity, I would write some notes on paper, some on text files on my desktop, some on my iPhone notes app when on the go. Notational Velocity organizes all of your notes on your desktop in a centralized, searchable location and syncs with Simplenote or WriteRoom on your iPhone. This seems like a little thing, but it really makes life so much easier. (More nerdy details here.) For Macs only.

5. FocusBooster – Focus on single tasks for 25 minutes apiece.

This app is based on the principles of the Pomodoro Technique, a time management system that challenges you to focus on a single task for 25 minutes and then give yourself a 5-minute break. Combining the features of a to-do list and a time-management coach, FocusBooster allows you to list out your daily tasks, and then it tracks your time as you work through them. When 25 minutes are up, an alarm sounds and you get a break. It’s an easy way to practice expanding your attention span without going overboard. For Macs and PCs.

6. Think - Limit your attention to a single application at a time.

This is an extremely simple app that’s akin to "Spaces" on a Mac. When activated, Think allows you to bring just one application into the foreground on your computer, while everything else is hidden underneath a nearly opaque backdrop. While you can easily shift between other applications when you need to, it creates a clean space for focusing on the task at hand. (It also works well in tandem with FocusBooster.) For Macs only.

7. FocusWriter - Create a distraction-free environment for writing.

If writing is something that you do on a regular basis, it’s incredibly useful to have an easy way to create a distraction-free setting. FocusWriter re-creates a word processor-like environment, blocking out absolutely everything on your screen except for the words you type on a simple grey background – all menus (date, timer, dock, etc) are tucked away until rollover. Despite its pristine appearance, FocusWriter does have the usual rich text editor features, such as spellcheck and word count. Plus a few bonuses like a daily writing goal (word count or writing time) and very gratifying typewriter sounds for each keystroke. For Macs and PCs.

8. Anti-Social - Block the social websites that are killing your focus.

Anti-Social is like a light version of full-scale Internet-blocker Freedom. Rather than blocking the Internet in its entirety, Anti-Social automatically blocks all of the known timesinks for a set period of time. Sites that are off-limits include Twitter, Facebook, Flickr, Digg, Reddit, YouTube, Hulu, Vimeo, and all standard web email programs. It’s not that different from Self-Control (see above), except that it comes pre-equipped with a blacklist (which you can add to, of course). If you can’t handle your Internet abstinence, you can turn Anti-Social off by rebooting your computer. For Macs and PCs.

9. StayFocusd - Curb the time you spend browsing time-wasting sites.

This extension, for users of Google’s Chrome browser, works in the reverse manner to Anti-Social or Self-Control. Rather than setting a period of time for which you CANNOT use the Internet, it allows you to set a period of time to indulge in time-wasting sites. Only want to give yourself 60 minutes a day for Twitter, vanity Googling, and updating your Netflix queue? This is your app. Rather like when you were a kid and only allowed to watch 2 hours of TV a day. For Firefox users, LeechBlock performs a similar function. For Macs and PCs.

10. Time Out - Take regular breaks to keep your focus sharp.

For optimal focus, we need to take regular time-outs to relax and rebuild our energy. Time Out is a super-simple application that runs in the background while you work. At set intervals (say, every 90 minutes), it fades in and gently reminds you to take a 5-10 minute break. You can also use it to remind you to take 1-minute "micro-breaks" to avoid eye strain from staring at your computer like a zombie for hours on end. For Macs only. -- How Do You Stay Focused? What apps are you using to keep yourself on track? (We'd love more PC-friendly suggestions as well.)