It's like Google Maps...for space. Wikisky is a draggable, zoomable, web-based star map. And if you click on a star or other object, it brings up a page with all the information you could want on it, including recent articles and astrophotos that contain that object. And it does lots more. Go explore.
Ever wondered what the Aurora Borealis sounds like? The northern (or southern) lights generate VLF radio waves as well as light. These sounds have been captured here as hundreds of free mp3 downloads, and they make amazing ambient soundtracks. Random clicks, whirrs, pops and whistles, direct from outer space. The site also features other "weather sounds" generated by lightning storms and such, and explains how you can get your hands on a VLF receiver to hear the sounds yourself.