ISS and STS-121 Discovery
 

According to the http://www.heavens-above.com/ web site, tonight (Wednesday July 5) should be a good opportunity for anyone with clear skies to see the space shuttle and the space station shortly before they meet. Choose your location or enter your latitude/longitude, and you can get very accurate predictions for satellite passes. I'll be out watching them go over my house a couple of minutes before 10pm.

(Discovery is actively maneuvering, so it might actually show up a little earlier or later than predicted.)

Re: ISS and STS-121 Discovery
 

I've found this applet very helpful as well in locating the ISS and Shuttle.
http://spaceflight.nasa.gov/realdata.../JavaSSOP.html