I happened upon the Baltimore Clear Sky Clock today. My first reaction was the usual unalloyed delight I have in discovering people more geeky than myself... and this is really a super thing, cross-referencing moon phase and cloud cover to show at a glance the optimal times for astronomical observing.
A guy named Attilla Danko (could you make that name up?) wrote it, for the good of humanity and the glory of being cited on some obscure blog like mine.
There are links here to topo maps, to satellite images, and a cutie-pie service that emails you whenever viewing conditions are at their best.
There are also clocks for 2839 other locations, in case you needed an excuse to call your brother in Seattle at 4am. "Get up! Get up! Now is the moment for Comet Giacobini-Zinner!"
(Have you created your own personal astro-calendar yet? Once you choose which types of events - meteor streams, eclipses, whatnot - you wish to keep track of, you can "import events into Outlook, your PDA or other personal planner software - to be alarmed before an event takes place." I'm alarmed already, frankly.)
But my second reaction was - damn - Baltimore blows for stargazing.