The blog world today is full of links to Edward Tufte's sparklines, a design element to display time series data in text. Read the article, it's interesting.
I occasionally worship at the Church of Tufte and have taken a lot of inspiration from his emphasis on simple and clean design. But many of his ideas seem awfully hard to apply well. A particular frustration is that many of Tufte's design elements rely heavily on 1200dpi multi-colour printing on fine paper. That's great, but these days all of my design is for 100dpi computer screens.
Tufte has written amazing and comprehensible books that have had a good influence on everyday design. But often when people cite Tufte it's just "oooh, pretty" without really thinking about where the ideas are applicable.