Q: Is there a way to look at a contact record and know if they are on a workflow?
A: Activities do show the workflow that they are attached to but nothing that shows on the main contact. One thing you could do is add a tag on the action of the first activity that contains the workflow name and remove it on the last.
I think adding and removing tags via the Action field would be more useful if we could take action on those tagged rather than just searching and identifying the tagged item