Like everyone said, mattermark. Especially if you're working on a project and not doing it professionally. You can also follow crunchbase or websites like built in chicago. They will give you insight into companies who have raised recently and how much.
However true VC's aren't looking at websites to follow trends, they are looking for patterns in the market that haven't yet emerged and are looking to follow a path. As example Google Ventures has pushed heavily into healthcare tech, now you're starting to see a lot of follow-on investors.