This is the reason I built my telescope; I stumbled across a usenet newsgoup purely by accident while searching for satellite photos of Manchester (UK), I was intrigued with the content and visited the Visual Satellite Observing Homepage (VSOHP) to learn a bit more. There are hundreds of satellites, rocket bodies and delivery platforms in low earth orbit, a lot of these are basically space junk and pose a potential threat to manned spaceflight (and also to working satellites), most of these objects are tracked and monitored on earth and the orbital data can be pulled of the WWW.If you go outside on a clear night after dark you will eventually see some of these objects flying overhead, in the summer you can see them at all hours-in the winter there is a shorter viewing window-(it's all related to reflection of sunlight-in the winter sun is much lower below horizon) So, with the right software and the relevant orbital data you can predict sightings, identify satellites and monitor them any time you want. There are all types of objects from functioning civilian and military sats down to spinning and tumbling rocket bodies and debris-a lot visible to the naked eye- some are constant in brightness, others flash and flare. With the ISS and space shuttle (plus chinese rocket capsules being tested for manned space flight) there is the added dimension of seeing manned vehicles fly overhead. So what do you need to start with? Nothing much!
Your eyes (and clear skies)
Your location-lattitude and longitude (see my astronomy links-all you need is your postcode)
A source for updated orbital elements (to run on the software)
Thats it, if you want to make positional observations and help update orbits you will need good large aperture binoculars or a telescope. The VSOHP has an excellent database covering all detailed aspects of the above in much more detail, with links to software, orbital elements, beginners guides, satellite details etc. If you want to give it a go before committing yourself to downloading software etc try Heavens Above, this site allows you to get predictions online, all you need to do is identify your town or city and then you can get star charts output for satellites on specific dates. Good Hunting and clear skies. Have a look here for interesting satellites visible from Marple