Traffic Sponge is a tool that informs you every time a blog you visit is updated. You load the rss feed url’s of the blogs into the software and when the blogs are updated you are notified.
There are two advantages to this system, one is that you do not have to keep trawling the sites to check whether they have been updated, and the second is that it gives you a better chance of being one of the first commenters on the blogs. This is the best place to be as a commenter as you are more likely to get visits from readers if you are within the first 3 commenters, as long as you have included your url in your signature!
Traffic Sponge is great value, a low cost tool that you will find invaluable in your Internet Marketing career.