Well, there's always playing a Killoren Gunmage with Charm the Arrow to replace Dexterity with Charisma to hit on ranged attack.
TWF with a a pair of Magelock Pistols would be fun.
"Look ma, I'm Revolver Ocelot."
Sorry about that. Anyway, another neat feature is that, unlike your standard familiar, you can enchant your freakin' pistols with whatever you want; I suggest Slaying of some kind. Or just have Slaying bullets on hand for the kinds of things you'll be fighting.. And you have Haste. You know, to get off 7 shots in a round?
Divine Power, added with Arcane Disciple (War), to grab yourself another attack. Dip a level of Cleric for access to Spellflower (let's you store 2 touch spells for as long as the spell lasts.) and 2 Domains. I suggest Planning to facilitate DMM Persisting of Spellflower and Divine Power, and Spell, for thematic reasons/Anyspell/ Greater Anyspell. I also assume that a Gunmage of Mystra woould be loverly (add Anyspell and Greater Anyspell to your spell list? Don't mind if I do.)
This class actually looks like it would be crazy awesome to play in a setting with guns.
Anyway, top elaborate on my Spellflower trick, it means you could store 7~8 Touch spells on bullets and then fire them all off. In one round. 7~8 Shivering Touches will ruin anyone's day.
Alternatively, an Elan Gunmage with Elan Retention, a couple levels sunk into Wilder, Deep Impact, and that feat that allows you to regain Psionic Focus as a move action. Spending power points to make ranged touch attacks is nice.
I suggest Up the Walls to add awesome.
And of course, dip some Cragtop Archer. Seriously, being able to smack anyone from here to the horizon with a touch attack is awesome.
Iajatsu Focus would be hilarious with this class; it would make you a gunslinger, just like in the Old West, only you would be murderfying things with 9d6+ damage and touch spells.
Hey, let's see if we can build the Saint of Killing with this class.
In all seriousness though, I would put this guy down as a high tier 3.