Google Scholar Citations provide a way for authors to keep track of citations to their articles. You can check who is citing your publications, graph citations over time, and compute several citation metrics.
Philpapers is a citation index for philosophy with the most complete index of the philosophical literature with over 2.4 million entries. It includes an open-access archive, PhilArchive, integrated with its citation index.
An OCLC index of papers presented at conferences worldwide