You want uncommon but not unusual? That's a bit hard. What about:
Elliot:
Ella,
Elly,
LeeOphelia: Ophie,
LiaMeredith:
Merry, Redy,
RedFrederica:
Freda,
Fred,
Freddy,
Rica,
EricaSylvia: Syl,
ViTamsin:
Tammy, Amsy,
TamCalliope:
Cal,
Callie,
LiaVeronica: Vero,
Ron,
Ronny, Nica
Jillian:
Jill,
LiaMargot:
Meg,
Maggie,
Madge, Mar
Constance:
Connie, Tancy,
StanHarriet:
Hattie, Hetty,
Harry,
Ria, Etty