It's getting pretty common to see a link below a database citation indicated how many authors have cited the article. It's a beneficial addition, as it can allow people to follow the article trail and discover other relevant articles, and it's also good for those who need to prove that their work is well respected and read by others.
Many of the large databases-Web of Science, JSTOR, Project Muse, ProQuest, MedLine, etc.- provide citation tracking information. However, in many cases, databases only track citation information from the journals they index. Even with databases that include a larger pool of refereed journals in which they're tracking citations-like Web of Science-the journals are specific to the database subject area. To feel that you've cast a wide enough net in your search for citations of a specific article (especially if they are not science or medicine related), you need to look through several databases for citation tracking information. This is a cumbersome and time consuming process, as is evidenced by the PDF "Finding Cited Authors in the Humanities & Social Sciences" linked from this excellent tutorial on citation tracking: http://www.library.uow.edu.au/resourcesbytopic/UOW026626.
Google Scholar casts a wider net in its citation tracking abilities, because it searches across disciplines and includes more than refereed journals. In a Google Scholar search one might find blog posts referencing the article, white papers, technical papers, and mentions on websites. While the information is not limited to refereed journal citations only, it can still be very useful to discover who is looking at a certain work.
While Google Scholar moves things in the right direction, wouldn't it be great to have a a tool that automatically updates citation tracking information, and crawls several meta websites that might provide more than Google Scholar? Enter Citation Tracker. This tool was developed by Panos Ipeirotis of NYU and he developed it to solve the chore of updating his own vita. Users can import their bibliographies, and the software monitors open-web sources to search for citations of those works; it also updates as new cites appear.
The list of citations can then be curated/edited by the user to eliminate redundancies and less-valuable references. It also locates uses of papers in syllabi that appear online (which can be valuable for demonstrating impact of scholarship). The tool can also be used as an alert service, to find papers of interest to the individual scholar. For more information, read his blog post
I put the above tools to the test using one of my articles--Multimedia Learning Theories and Online Instruction Nadaleen Tempelman-Kluit. College & Research Libraries. Chicago: Jul 2006. Vol. 67, Iss. 4; p. 364
Results:
1.ProQuest: Cited by four -one recent (2009, scholarly) the others white papers from Universities
2.Google Scholar: Cited by fourteen- a mix of scholarly journals and blog-type posts, including articles accessed via csa.com and institutional repositories.
3.Citation Tracker: Cited by one hundred and sixty five: http://citation-tracker.com/publications/5d995819-2f0e-4cff-9c40-1e27aaaccc60/citations/. Not all of them are peer reviewed publications, but there are many more publications listed than the above tools provided, and then a plethora of other mentions from across the web.
Seems like a valuable tool.