The best guest is one who comes with a gift. Instead of the usual candle or wine, impress your host with something unexpected.
Something sweet: Paulette macaroons (beyond delicious), & Sees Candy ( Enough said)
Something unexpected: Monogrammed cards by pickettspapers.com, & a Perfume Gun by  Frederic Malle 
Never fails: Good olive oil (I prefer Castelas Organic), & photo frames by Two's Company