However I suspect this is not a serious source of income.
Correct, I'd like to think one day another website I'm building will provide that! But at the moment, this site is not self sustaining.
and said that there were illegal clicks on my website
I don't doubt it - I am prepared for this and what I expect is happening, is that Google fires off this e-mail pre-emptively without any investigation. The fraudsters back off and the legitimates fight their corner. Guilty until proven innocent?
Another convenient option is to display a vertical bar at the right of the main layout.
Yep I am really toying with that idea - it's less intrusive.
Really though I'm looking for a better paying provider based on CPM rather than PPC.