If you are interested in tracking a reference (say a seminal work or an article of your own perhaps) you can use the cited references tab in these databases.
Web of Knowledge
You can also use a citation tracker if you want alerts (emails) sent to you everytime a reference you are interested in gets cited. Make sure you sign up for a personal account- and then you can choose the settings you require.
This should help you keep one step ahead!
If you need any more information on how to set these up- let us know.