Site blockers are an old-school Web technology originally designed to keep kids from stumbling onto porn while using the family PC, but they're gaining popularity with personal productivity buffs because they add a helpful layer of reinforcement to one's own sense of self-discipline. Will it totally prevent you from wasting time? Of course not; if you want to get to Facebook, you're not going to let some browser add-on stand in your way. But if you have to disable a blocker or switch browsers to get to Facebook, you'll at least have to think twice about how you're using your time.

All major browsers have available plug-ins that fulfill this role. On Google Chrome, I like SiteBlock, which gives you a simple box to type in the URLs you want to filter and an option to unblock them for a limited amount of time at regular intervals throughout the day. It's a nice approach that leaves you just a little time for self-indulgence. On Firefox, a similar app called BlockSite does pretty much the same thing as Chrome's SiteBlock.

includes a feature called Content Advisor, which you can configure to either always allow a site (even if IE sees it as a security risk) or always block a site. In IE9, click the Settings button, then Internet Options. Under Content, click Enable for Content Advisor and click the Approved Sites tab. Type in a URL and click Never to block it.

This strategy works best when you use only one computer for your work, so you don't have to worry about disabling a blocker when you're not working. One way of making this work on a multi-purpose PC is to use one browser for work, and another for play, essentially creating a cognitive division between your productive time and your leisure time.

For more ways to stop tech distractions, check out these .