Anyone know of a good spellcasting archer PrC?

[Voodoo]

The War domain grants you your longbow proficiency (and weapon focus) as long as you choose a deity with the appropriate favoured weapon, and if you are going the elven route the Elf domain nets you point blank shot.

 

[beaver1024]

Elven Cleric with Zen Archery feat (from CW).

Elven Cleric with Elf and Time domains or Elf and Planning to go the Divine Metamagic Persistant Divine Power route.