The Shroud...Marvel has toyed with the character for a long time. First it was with Super-Villain Team-Up, where he had a Scourge-type thing setting up before Scourge came around...and they did not pull the proverbial trigger. Then it was recruitment with the West Coast Avengers, which fell flat. Then it was the early '90s with the Spidey titles. The latest was Shadowland and Civil War. Cool power set, nice Batman-style background, connections with the underworld.
Blackwulf...been saying this for a few years, but the Secret Invasion stuff could have been so much better had Marvel explored the connection between the Deviant Skrulls, Deviant Earthlings, and the Dreaming Celestial, like was started with the Blackwulf series. Great character from the 90s, has not been seen since his series ended.
Bloodstone...And no, I'm not talking about Elsa. I'm talking about going through a historical quest with Bloodstone. Go through the history of the Marvel Universe, making him a bit of a catalyst for many of the events, especially since he was around since basically the beginning of man.
Scorpion...The female version from the latest Amazing Fantasy series. Used her a little during World War Hulk, but is underutilized and since she's still a teenager, could be a good way for Marvel to market to the young female audience that they have been trying to convince the past couple of years.
Man-Wolf...With Marvel's focus on the cosmic titles coming up, John Jameson should be involved. Period.
man I didn't think anyone remembered Blackwulf! I always liked the Shroud, and it does seem everytime Marvel kinda pushes him, they kind of really doing doing with him in the longrun.