ERIODICALLY, BBC 7 Radio will air a (semi-)new Sherlock Holmes adventure which you can listen to online in their “Listen Again” section, essentially a seven-day archive. So, while you can, visit the BBC 7 - Listen again page to hear Clive Merrison as Sherlock Holmes and Michael Williams as Dr. Waton in Bert Coules’ adaption of the last Holmes adventure:

Sherlock Holmes: His Last Bow
His Last Bow: 1914. The services of a certain bee-keeper are called upon to help his country in her darkest hour.

Link (almost half-way down the page, and in offered in RealAudio format). These adaptions are top-notch and generally quite faithful to the original stories by Conan Doyle, or as much as possible given the medium and time constraints.

(Thanks to Pauline in the WelcomeHolmes mailing list for the heads-up.)