Heather Parton, also known as Digby, founder of the Hullabaloo blog, has compiled a list of planned Congressional investigations. They have a common thread. The list is organized by House committee.

Oversight:
Michael Cohen payments
Trump International Hotel lease
Census citizenship question
Prescription drug prices
Security clearances
Russian sanctions

Intelligence:
Russian collusion
Border wall
Russian sanctions

Judiciary:
Protecting Special Counsel Mueller
Family separation

Way and Means:
Trump tax returns

Natural Resources:
Puerto Rico reimbursements

Energy and Commerce:
Family separation
Environmental Protection Agency and climate change

Homeland Security:
Border security

Foreign Affairs:
Russian sanctions

Transportation:
Trump International Hotel lease
Russian sanctions

Voting matters.