If you're using regression models but want really hone your regression-fu this short course on Regression Modeling Strategies by Frank Harrell looks really interesting. Frank is the author of the book Regression Modeling Strategies which is my go-to reference whenever I'm doing regression of any kind in R, so it's definitely worth a trip to Nashville to if you want to learn how to make regression really work. Registration closes March 1, and the 3-day course begins March 31.
By the way, if you haven't tried them already check out Frank's rms package (formerly the Design package, a package of regression tools to accompany the book) and also his Hmisc package. Hmisc has a bunch of useful utilities (PDF) to extend the R language in various ways -- the tools for creating attractive tables in LaTeX are especially useful.
Department of Biostatistics, Vanderbilt University: 2010 Upcoming short courses in Regression Modeling Strategies