I have seen a couple of web articles pointing out that Europe's ATV "Jules Verne" is now in a parking orbit 2000 km ahead of the ISS. This offers the possibility of seeing both spacecraft a short time apart when they pass close enough to your viewing location. I've seen the ISS and shuttle separated on a close pass (STS-118 last summer), and it's a very cool sight.
But how to know when and where to look? There are several web sites that can tell you when the next visible pass will be for various satellites including the ISS (and shuttle and ATV when they are up). There's a new one from SpaceWeather.com that is especially simple for US and Canadian viewers. With Satellite Flybys, you simply enter your zip or postal code. The results are not too detailed but they give the basic information for the brightest objects - the satellite name, the rise time, the direction to look (like SSW), and the elevation. It seems to exclude low-elevation passes that are near the horizon and hard to see. For more detailed tables, NASA's SkyWatch applet is great. It will also provide a star chart with the object's path if you click the SkyTrack button. The sightings help page includes viewing tips and a nice 3D diagram.
Another good one is heavens-above.com which has tables, sky charts, and ground track charts. The latter are useful in understanding why the ISS shows up where it does with the predicted elevation. The example above is for next Wednesday the 26th which should be a decent pass for me if the weather cooperates (max elevation 51 degrees). The circle shows the region where the object is at least 10 degrees above the horizon, and the solid line is where it is lighted by the sun. The dashed area is in the Earth's shadow.
P.S. I was driving to Wilton, Connecticut Wednesday evening but skies were clear and I remembered to stop around 8:20 pm. I pulled into a neighborhood with a good view to the south, and I saw Jules Verne sail by, followed a few minutes later by the super-bright ISS. I missed seeing the shuttle because Endeavour had already made its deorbit burn and was about to land at KSC just 10 minutes later (about 8:40 pm EDT).