For my Holy Champion of Althares I'm still deciding what item I want.
Either boots that boost acrobatics, or a dictionary/book of languages to get +2 to linguistics.
For my Psionic Inquisitor, she will be getting a medallion with the symbol of the Legio Lex Talions that gives +2 to intimidate, because everyone fears the inquisition.
As for ideas for other people here are some that I thought of:
Athletics or Accrobatics: Boots
Deceit: a mask, veil, or other face covering
Beast Lore or any knowledge: a book or scroll with related information
Stealth: Cloak or boots
Seamanship: a pirate hat. Because that just makes you look cool. XD Or a sextant.
Etiquette: a book of customs of a particular nation.
Streetwise: a tour guide book. Something with maps and info on the location.
Artisan: tool kit pertaining to your trade.
Heal: Healers kit
Perform: Instrument or dance ribbons. Related to your perform skill.
Larceny: lock picks or gloves