Web applications are basically software programs that you use on the Internet. You don't have to download them to your computer. 

There are "webapps" that can: keep you from getting lost, keep you on task, keep you organized, find you great deals, and just about everything in between.

One very popular application is the photo sharing site, Flickr. Flickr is extremely easy to use, free, robust, and extensible.

What I mean by "extensible" is you can actually use Flickr and other webapps (in simplistic terms) as building blocks to make other even more useful and powerful webapps.

Here's an example of this extensibility, Microsoft recently acquired an application (PhotoSynth) that "takes a large collection of photos of a place or an object, analyzes them for similarities, and displays them in a reconstructed three-dimensional space." That "large collection of photos" is... you guessed it, at Flickr.

What makes PhotoSynth such a big deal? Well do you remember that trip you took to DisneyWorld last year? You will be able revisit the trip, on any particular day of your vacation, and in it's full 360 degree glory. You will be able to zoom in and see extreme detail (you may be able to see faces-- quite possibly even your own).

Why I get so hyped about it is it's developers used a simple idea (shared photos), expounded on it and made an incredible tool.

Here's another, less grand "MashUp" I found tonight, it's 123FLICKR.com. This application simply allows me to show you a gallery of my latest "not work related" images on Flickr.