For those of you who like their theorycrafting then this thread is for you. Throw all your build ideas and discussion in here and to start with I'll throw in one of mine:

The Mad Bomber (PvE/WvW)

Trait Points: 30,0,20,0,20Major Traits: Explosives: 33% to cause burning on crit

+10% damage to explosives
Increase AoE of Bombs and Mines/Grenadier
Inventions: +5% toughness to power
+10% to speed while in combat
Toolkit: 20% reduction in gadget recharge
+10% speed while using an unarmed kit

Skills: Rifle skills, Med Kit, Bomb Kit, Mine, Utility Goggles, Mortar/Supply Crate
Gear: Power and Crit chance/Crit damage

A fairly simple concept. Run around your target(s) dropping bombs while using your speed to stay just outside of melee range while keeping them within the AoE of your bombs. By switching the last major trait and the bomb kit for the grenade kit, you can get a fairly decent long range build. The grenade set is more suited for WvW where the AoE and long range will be more effective against the usual zerg.