Project management for Bauhaus fans (the School, not the rock band). This collective has built elegant web-based applications for project management, task management and group chat -- BaseCamp, TaDaLists, Campfire. Software reduced to useful essentials. Their minimalist aesthetic has spread much further than their 500,000 users (they've nudged it along with their blog Signal-to-Noise and their e-book Getting Real). Team members are also responsible for the red hot Ruby-On-Rails framework which underpins lots of web 2.0.
37Signals was originally a design and usability shop. After creating a productized usability assessment (a flat-fee, single page review), they developed some internal project management tools. Those eventually 'went public' and now are the core of the firm. Like the rock band Pavement, they work as a small, often-virtual, non-hierarchical hive.
Dimensions: 7 people x 7 years x $ NDA (but definitively profitable)
Customers: Software development teams, individuals
Location: Chicago [West Loop] + www.37signals.com
What's Next: A different kind of CRM application - named Sunrise