If you're looking for a clear, fairly comprehensive introduction to just about any health topic, the Mayo Clinic site is usually a good bet. This introduction to asthma is no different, and the section on medications is particularly good. As with all Mayo Clinic pages, however, it's a little bland and a little too straightforward to really be engaging, but who says education has to be entertaining?

An excellent article about asthma. It covers testing, medicine and preventative measures. I highly recommend this easy to read, but very educational article.

Good overview as an introduction to asthma.