We originally learned of Tandy's visit earlier this week. He is a cornerback who wasn't invited to the NFL Combine but is now drawing interest from several teams.
As for Kelly and Oram, they are the latest offensive linemen to come in for visits. Before today, the Lions had already hosted OT Kelechi Osemele, OT, OT Kevin Murphy, OG Brandon Brooks and OG Amini Silatolu for visits, so it's pretty clear they are taking a serious look at adding help on the O-line this year.
Go here for a look at all of the Lions' pre-draft visits.