It sounds like you guys have quite a large group already, but if you'd accept one more...
I actually have a ton of ideas for this. One could be some sort of culinary genius (made useful to the Omnimen through the fact that they can disguise the taste of poison or similar things, they would be capable of making food literally 'to die for'), or focus more on the poison side and make them an expert biologist that knows every plant on the earth and what it can do. Expanding on the disguise element, on the other hand, an expert makeup artist would be cool. They'd be able to transform people who need to go undercover.
To try something a bit more physically-oriented I might want to create some sort of extremely flexible person (I feel like that might have been claimed already, but I didn't see something like it when I read through the posts briefly) but I'd also like to try a ventriloquist... That might be borderline superhuman, but I think it could be realistic for somebody with extremely flexible vocal cords and a good ear for accents / sounds to be able to imitate most things.
Then there could be a person with photographic memory or something similar, which could be taken off of the superhuman side by limiting it to words / pictures / numbers depending on the character. A possible addition to that could be extremely good facial recognition skills, which would probably be the doom to the makeup artist that was mentioned above since they'd be able to see through disguises.
To lean on the more insane side though, I think it'd be interesting to play an expert pyromaniac. xD Somebody who would know how to light a fire basically anywhere in any situation might be useful.
BUT. All of that is just if you are looking for more people haha. So, mind if I join? And, if I can, do you have any preference to which idea I use?