1. The first fic is where Widow has family (a younger sister, maybe) living in NYC. A mob guy wonders why this one house/business isn't paying protection and they are told because it is the family of the Black Widow. I think that Bucky looked out for them on occasion too (or maybe they were Bucky's family instead and it was Widow looking out for them. Either is possible. And Soldier might have had something of a cameo in the story as well.) I do remember reading it before the WS movie came out and I'm almost positive it was complete and not part of a series but that's all.
2. FOUND!! (Link in comments.) Dummy lifts Mjolnir. Somehow Thor leaves Mjolnir in Tony's lab and the bots are left alone. When the bots are attacked in the lab, Dummy manages to lift Mjolnir and use it to protect the other bots.
3. FOUND!! (Link in comments.) Thor brings the W4 to visit the Avengers. He tries to set Sif up with Steve but Steve seems to be clueless. Sif gets angry with Thor about setting her up as a joke and asks if Steve has taken a vow of celibacy (or something like that); they finally decide that Steve is just extremely shy (sort-of like Balder, iirc.) Sif and the W3 are pretty decent too, which is a nice change.
Thanks in advance!