The Disciple of Thyrm, while a bit specialized, is a great 3-level dip for Fighters and other noncasters. It has 5th level spells in 10 levels, a decent (if small) spell list, full BAB, and gives a special bonus to greataxe users (specifically, double Strength modifier on damage rolls instead of 1.5).
It does require Weapon Focus (Greataxe) and either the Cold subtype or the Cold Endurance feat, but the Cold Endurance feat is a Fighter bonus feat if the Cold subtype would be problematic (although I'd sooner use the old Frozen Berserker+Blazing Berserker trick, even if it costs more feats).