You should try a search on "acoustic guitar" here as this question has been asked before. I'll add Rory Block (pretty much anything - When a Woman gets the Blues is great), Tim Reynolds and Dave Matthews if you like Dave - there's a great live album at a Luther College, Gillian Welch on the country side (her guitar accompaniast David Rawlings is fantastic), Patty Larkin has some great rifs on Agogo.
Marco
Marco