From The Hill:

The House ethics committee has started investigating 15 new cases of alleged misconduct so far this year while probing 11 cases held over from last year, according to a new semi-annual report the panel released Friday.

Only two of the new cases are publicly known, an investigation into two trips to the Caribbean taken by several members of the Congressional Black Caucus, and a review of allegations involving links between campaign contributions from PMA Group, a now-defunct lobbying firm whose offices were raided by the FBI last fall, and its clients and earmarks lawmakers steered to its clients.  In both cases, the ethics committee issued releases acknowledging the investigations.

So, that leaves 13 that aren't publicly known. There are plenty of possibilities. And, we're anxious to see if the House Ethics Committee actually takes any action against unethical behavior.