We are building a little something here at work and I needed to throw together a quick UI design before things got heated. In the past I’ve come across Visio designed application or a mix of visio & photoshop. I found some decent visio stencil sets for web applications but I just wasn’t satisfied with the end result and didn’t want to jump into Photoshop to make things prettier. I wanted a something simple, that understood I was building a web application, & a low learning curve. That’s what I found with Balsamiq Mockups. I highly recommend you give it a try.