GottaBeMobile.com, which is dedicated to news & reviews of netbooks, tablet PC's, and all things multi-touch, has a new section called Real Users that looks at "how everyday people are using mobile technology to improve how they work and communicate."
Without a doubt, it has improved my workflow. Colorizing a variety of design ideas at an early stage of the design process both helps me think through design issues myself and share early concepts with clients. I also often use the tablet to integrate photos of real materials into my sketches. This ensures that we are on the same page. Prior to using the tablet, I would more often use CAD generated computer renderings in early design discussions with clients. CAD geometry is significantly more more labor intensive. Additionally, some clients feel more reluctant to suggest changes when they see the more "polished" look of a near photo quality computer rendering. So with more feedback from clients earlier in the process, I now have a smoother overall design process.