What about Google Scholar?
There are different opinions as to the value of google scholar.
Critical: Jacso, P. (2006), "Deflated, inflated and phantom citation counts", Online Information Review, Vol. 30 No. 3 pp. 297-309
Supportive: Bauer, K. and Bakkalbasi, N. (2005), "An examination of citation counts in a new scholarly communication environment", D-Lib Magazine, Vol. 11 No. 9
If your discipline is not well covered in the other citation services then you should check Google Scholar however, it is MOST important that you check the actual cited by link to make sure that they are scholarly citations to your work. They could be undergraduate papers, someone else's work, pre or post prints that you have already counted
We think it is easier to search using a software programme called Publish or Publish which has been created by Anne-Wil Harzing, Professor of International Management at the University of Melbourne.
It is available for download at http://www.harzing.com and uses Google Scholar to obtain the raw citations and then analyses those.
Eg
You can also search using the Advanced search in Google Scholar
Type your name as the exact phrase. If you publish a lot with just your initial try "lemony snicket" OR "l snicket". It must be entered as written, with the capitalisation and inverted commas for this to work.
Eg
Do not use the subject areas or author searching fields as you will eliminate many useful results.
If you have a widely shared name then you might need to add some extra keywords in the "with all of the words" box.