When Bill says that puns used to be the highest form of humor he is referring to a similar statement made by Alfred Hitchcock in a 1972 interview ("Puns are the highest form of literature").
Hoyt's mother describes his skin as being "whiter than Desitin". Desitin is the brand name in the US of a barrier cream sold to prevent diaper rash. It's main ingredient is zinc oxide, also used to make white paint.
When Bill takes Sookie to Fangtasia for the first time a remix of Blue Oyster Cult's "(Don't Fear) the Reaper" can be heard playing.