Time for some space geekery. Recently the International Space Station has installed the S6 truss and associated solar panels. (That's the sixth truss segment on the starboard side, and the last pair of solar panels - the fourth of four). See http://en.wikipedia.org/wiki/Integrated_Truss_Structure for horrendous details...
What does all this mean? Well, all that extra solar panel area means that ISS now reflects a lot of sunlight, and under some conditions is now brighter than Venus. If you're looking in the right direction at the right time you can hardly miss it - something as bright as Venus moving pretty rapidly across the sky. Worth looking for, even with fairly light skies.
There's a number of sites that will generate sighting information for it. NASA has one at http://spaceflight.nasa.gov/realdata/sightings/ - it uses Java. http://www.heavens-above.com/ will also do the job and also calculates Iridium satellite flares, another thing that it's worth looking out for. In both cases you'll need latitude and longitude for your location to get the best information; easiest way to get this (for me) is to go to http://www.streetmap.co.uk/, find your location and then click the "Click here to convert coordinates" link.
