There are plenty of free web services that allow you to easily share your desktop with others, but new webapp Screenleap simplifies screen sharing even further. Screenleap allows you to share your desktop with as many people as you choose, without signing up for an account, downloading and installing anything, and does it all for free.
The only software you'll need on your system to use Screenleap is the Java Runtime Environment, which most people already have. The first time you use Screenleap, you'll have to grant the service permission to run in your browser, but aside from that, the service is completely hassle and setup-free. Just visit the website, click to share your screen, and go.
Once your screen is shared, you'll get a link to send to as many people as you want to see what you're working on. The URL is only active while your screen sharing session is live, and while you don't get advanced tools like annotations, zooming or chat, once it's running, you do get a ridiculously simple way to share what you're working on with others.
Granted, there's no shortage of options for screen-sharing and collaboration. Google+ has it, and we've examined other options in the past, like TeamViewer, LogMeIn, Join.me and GoToMyPC. Even if you prefer one of those other options, Screenleap may be worth keeping in the arsenal when you don't have the time or resources to fire up one of the others.