I have my projects on github, and they're public. How would I know that my projects have been cloned, and by whom?
There is no way of telling who have cloned your project.
But, Github provides basic statistics about visitors and clones in 'Graphs' option on your repository. Here is a link.
Also you can see who has forked your project: A number showed on top right corner on your repo present on Github. Go to Graphs->Members to check out who forked your repo.
Hope this helps.