I have been using Balsamiq (a mockup tool) a lot since I purchased it a few weeks ago. It had the likeability factor from the off, and has proved pretty useful.
Before using Balsamiq I had experimented with other tools but mostly I tried blundering and man handling applications such as Visio or Dreamweaver in to producing mockups. The biggest problem I had with those tools is that they got in the way. I spent more time trying to get them to do what I wanted, than I did brain storming, capturing an idea or mocking up a screen.
Balsamiq is a little different in that it is very specialised; it is designed to do mockups and very little else.
It has almost no learning curve to get started, and produces nice looking mockups. As a result it doesn’t get in the way, and you find more of your time is thinking about your idea or your page, rather than worrying about the tool
Then there is the produced mockups themselves. There is a great advantage to having a mockup that looks informal and almost hand drawn. Everybody who looks at the mockup knows its a mockup, and not the first attempt at a design. This means you can discuss more about the idea and how it might work than perhaps discussing fonts, and
nit picking about different elements.
I used Balsamiq to create the initial mockups for Ask Jon Skeet. It is probably an over-simplified example of how you might use Balsamiq, but even for something this simple it boosted my productivity. I have zero design skills, so I lean heavily on web designers when it comes to building a website. In the past most of the information I have given the designer has been textual or verbal, but providing a mockup of a screen can help immensely and is an easy and quick way to convey an idea more clearly.
An example of how the homepage for Ask Jon Skeet went from concept to design.
Balsamiq are a small team, and seem to be pretty agile – they usually release updates each week. You can read more about the latest developments on their blog.
They also seem to be open to new ideas and suggestions. I am looking forward to when they introduce linking mockups, and allowing some sort of template inheritance.