I stumbled across the the fantastic diagramming web-app Diagram.ly through my RSS feeds several days ago. GigaOm had a nice article covering a load of web-based apps and piqued my interest in several new tools. I'm generally not a fan of web apps simply because I do not always have a network connection and often the app disappears when the VC money dries up. However, I also appreciate a well done cross platform application.
Diagram.ly is a nice middle ground between the dulcet OmniGraffle and the horrific Visio. I've mentioned it before, but I'm stuck in the grey area between a Mac at home and Windows machine at work. Cross platform access becomes a challenge at times. I would much prefer to work in OmniGraffle but that's not an option during my work days.
The feature set is quite deep and impressive. Drag and drop is fully implemented. There is a reasonable amount of customization and object formatting. Importantly the application allows users to export their diagrams to a variety of formats and save them locally. I hope they come up with a business model that keeps the doors open. This is a wonderful tool for quickly making diagrams for presentations or simply outlining a workflow.