Dan Cederholm is a high-quality designer with great jumpstart material. Namely, his books "Bulletproof Web Design" (http://www.simplebits.com/publications/bulletproof/), and "Web Standards Solutions" (http://www.simplebits.com/publications/solutions/).

If you can afford the time and expense, a one-day Carson Workshop from a CSS master can help a lot. This one is already past, but for example: http://carsonworkshops.com/design-dev/clarke/14May2008.html

For off-the-web inspiration, study Edward Tufte (http://www.edwardtufte.com), architecture (for example, Christopher Alexander: http://en.wikipedia.org/wiki/Christopher_Alexander), and cartography (peruse a great atlas like The Atlas of Oregon: http://geography.uoregon.edu/infographics/projects/atlasPrin...).