Long Overdue Update: This post has turned out to be one of the all-time most popular on my site, which surprises me to no end. Who'd have thought my crummy heatsink-and-tin thermal cycler would be cooler than isolating glowing bacteria or printing a 52,000g centrifuge? But, who am I to question human interest. It's not like my interests are particularly normal anyway. However, I do think this post needs updating, since people keep returning to it and asking questions.
For a while preceding buying my own Arduino, I spent my time looking at all the cool projects people have used them for on the Make blog, Fashioning Technology and the Arduino wiki itself. Although I love all the projects that showcase the artistic use of electronics, and I'm impressed with the more utilitarian uses also, I see great untapped potential in the Arduino as a replacement technology for certain niches where equipment is prohibitively expensive.