The Sept. 24, 2005 issue of New Scientist has an article about anosmia, the loss of one's sense of smell. It's a first-person account of losing the sense of smell after a viral infection, as well as a hopeful but untested treatment under cognitive neuroscientist Robert Henkin, at the Washington DC Taste & Smell Clinic. Henkin believes that theophylline might restore the sense of smell, and in a few cases, it has. There have been no large-scale clinical trials, but the author is now happily smelling coffee, perfume, and newly mown grass.
The unbearable absence of smelling, by Mick O'Hare. Available for a fee from New Scientist's web site, or in LexisNexis.