In just a few hours the ISS (International Space Station) will be sweeping overhead where I am, and I have clear skies tonight. For others inclined to do naked-eye viewing of manned orbital craft (or unmanned, or perhaps planets are your chosen targets to watch), there are a few resources you might find useful. First off, there is NASA’s Human Space Flight App, updated with the latest orbital tracking data, not only for the ISS, but also the Shuttle, the Hubble Space Telescope, and a number of others. You can reverse that as well, using their Realtime ISS Photos page to see an image of what is below the ISS right this moment. Note that the ISS location is in realtime, but the pictures are from an archive, possibly even the EarthKam; and the European version is the EuroKam variant. In Europe or the rest of the world you might want to use the ESA ISS Seeker applet. Which interestingly enough is built on the next tool I wanted to mention…
Heavens Above isn’t just for multinationals or government agencies; you can create your own account there, and customize your interface for your own interests. It is an extremely powerful database and toolset, so much so that even NASA links to them, and this site makes the wonders of the skies available for everyone to know and observe. They did a killer job on the setup parameters and the graphic output, making it both very easy to select your location and objects of interest, and even easier to understand the results it gives you.
There are a number of other online satellite/planet tracker software packages I use on a regular basis, the next most frequently visited being Night Skies, the Sky and Telescope interactive extension of their This Weeks Sky At A Glance page.