SMART
SMART (a Simple Modular Architecture Research Tool) is an online tool which allows the identification of protein domains and the analysis of domain architecture.
You may use either a Uniprot/Ensembl sequence identifier (ID) / accession number (ACC) or the protein sequence itself to perform the SMART analysis service.
Here is a link to the homepage of the site: http://smart.embl-heidelberg.de/
More information about the site, and further literature relating to its use can be found here: http://smart.embl-heidelberg.de/help/smart_about.shtml
NB: This online tool is extremely useful (and expected to be used) when completing the bioinformatics module in stage 2 (CMB2005)