Maybe Rogue 3/Fighter 4, using Sneak Attack +2d6 with each Rapid Shot barrage, every other round..... Between each barrage, use Bluff to create a distraction to hide (standard action), then a Hide check (at -10 unfortunately) with a move action to get yourself hidden (preferably, surprise the enemies first and win initiative, for a free barrage in the first round). 5-foot step out the next round for a full-attack.
Could have 10 ranks each in Bluff and Hide (taking rogue levels at 1st, 4th, and 7th to spread out the skill points)... A Cloak of Elvenkind would help out with the Hide checks, and of course Boots of Elvenkind would be useful for general sneaking. Feats, as a human: point blank shot, precise shot, rapid shot, weapon focus (composite longbow), improved precise shot, weapon specialization (composite longbow), and improved initiative.
Lessee.......14 Str, 18 Dex would be: full attack with +1 flaming composite longbow, within 30 feet with sneak attack and rapid shot: +11/+11/+6 for 1d8+2d6+1d6+6 damage. Some Lesser Bracers of Archery would add another +1 on the attack rolls with your bow, and of course higher Strength or Dexterity would be useful (might go for a +1 composite longbow without the flaming quality, and instead get Gloves of Dexterity +2 and Gauntlets of Ogre Power +2).
Just one idea, of course. Doesn't fit if you expect enemies to be surprising your party more often than the reverse, or if you don't expect to have much to hide behind during combat.