Free Online Tool to Check How Many Back Links Your Website Has
As Part of the Promotional side of Web development, it is very important to constantly keep an eye on back links, as these play a big part in how you rank within the search engines. Saying that, it is important to note that the quality of the links is arguable even more important. E.g. 100 back links with PR0 versus 10 backlinks with PR2, the latter would be much better for your own rankings.
http://www.searchenginegenie.com/backlink-checker.php
This site also has a wealth of other tools that are useful, these will be covered in other articles.