Web Site/App Modeling Tools

[cacibc]

All,
My project has recently taken over a large web-based workflow application with the job of retooling it to a new technology platform (specifically Classic ASP moving to ASP.NET 2.0). One of the things we ran into right away was the lack of cohesive documentation by the original builder. As a result, we are attempting to map out the entire Web app/site, in terms of flow, functionality and interface design. To get everyone on the same page, we’ve defined a core set of common web objects (things like Labels’, Grids etc) and are planning to split the app up into sections for each team to review and perform the actual data capture. What I would like to have is a piece or pieces of software that would allow us to capture the data in detail in a structured manner (ie some kind of entry form or wizard) and then allow for modeling of flow and visual layout. Does anyone have any recommendations? We’ve investigated a good number of UML tools and while they would allow us to build functional models, they don’t seem to have any means of defining and capturing specific object properties.
Before we go and build an in house solution, I thought I would ask since it seems like this would be a common desire amongst web site and application developers.
Any suggestions would be tremendously helpful.