Web of Science - Covering 12,000+ scholarly journals, plus selected books and published conference proceedings in all academic disciplines, Web of Science combines nine citation indexes that permit searching for articles that cite a known author or work, as well as searching by subject, author, journal, and author contact.
Search using the Cited Reference Work tab to find the number of times your work or other authors work has been cited,
Scopus - International multi-disciplinary indexing & abstracting database for scientific, medical, technical, and social sciences. Coverage includes journals, patents, and websites (18,000+ titles) from more than 5,000 publishers. Users can perform cited reference searching, citation analysis, get h-factor for authors, journal analyzing, etc.
Google Scholar - Article results also include the number of times an article or author has been cited.
If an author has set up a Google profile, their most cited research papers will appear in their profile. Look for a link in author's name in the citation to view their profile.