Taking inspiration from Firefox and Chrome tab-navigating shortcuts, how about similar behavior in PM since contact sheets are equivalent to tabs?
A lot of shortcuts are already taken, but here is an idea for mac:
go left one contact sheet: alt-cmd-left arrow
go right one contact sheet: alt-cmd-right arrow
jump to # contact sheet: cmd-shift-#
Functionality could also include the ever useful "undo close tab (contact sheet)". I'm sure there are common sense pc equivalents similarly available.