Dragonheart Mage
Races of the Dragon. It dovetails with the draconic heritage feats (which are all reprinted and expanded in Races of the Dragon) and it simply amazing. I'm playing a 16th level one, and its a wonderful class.
In a nutshell. 8/10 caster levels. Good Fort(!) and Will, d6 HD, Ok skills (search, gather info, all knowledges). Weak Bab.
You get the dragon breath feat free (swap a spell slot to do 2d6/spell level in damage, based on ancestors breath weapon Ref save = spell save DC minus bonuses like spell focus). This goes up in level (2d8, then 3d6 at 10th level.) In addition, you get a couple bonus feats that can be used on draconic heritage feats.
Sure, its still a feat-sink to get a good dragonheart mage going, but well worth it when you can blow a 7th level spell slot and do 21d6 fire in a 30' cone, ref save 17+cha mod. Granted, thats at 17th level (you lose two caster levels, so your spellcasting progression is further slowed). but its better than the disciple.