Balsamiq is a great tool for making mockups. I have been using it for a couple of years and find it great for quickly getting rough ideas down and communicating layouts with the rest of the team and with clients. It’s also possible to screen share with clients and make changes with them so that they can see different options, a great way to work collaboratively.We recently discovered that Balsamiq have a great policy for making their software available to not-for-profits like us.
 

They have kindly given each of us at Aptivate a license so that we can make mockups for our projects. They talk about the benefits they have seen from sharing their software on the Balsamiq blog.  

We think this is something more software companies should do!