I think the article you are looking for is "Transversed Arcana" in Dragon #357, Pages 88-89.
Impromptu Metamagic Chose a metamagic feat each day. You can use that feat for free & spontaneously a certain number of times: 5 - metamagic level adjustment. You will not have to decide on which spells you apply it during preparation, but on the fly just before casting. This might you could spontaneously empower three spells, or extend four. Becomes even better in conjunction with other feats that decrease metamagic costs.
Two important restrictions apply: You may not use other metamagic feats that day (but you can use the same feat with other spells as usual, preparing them), and you must have spell slots of the level that the modified spell would use if you didn't have the feat, so no free empowered ray of enfeeblement on L1.
School Mastery Choose a school of magic (specialists must take specialization school). Cast all spells of this school at +1 Caster Level. In addition, gain minor effects depending on school.
Abjuration: Double the duration of all non-instantaneous, non-permanent spells you cast on someone other than yourself.
Conjuration: +2 Dex/+2 Wis for any of your summoned monsters.
Transmutation: +1 DC for any spell that you cast that alters a creature's form, kind, or type.
Eidetic spellcaster. This feature can be really cool or totally worthless depending on your DM: You do not need a spellbook. You learn spells normally, have to pay the normal costs for copying spells ('for incenses' instead of paper & ink) and so on, but you commit them to memory. You can prepare any spell you know from memory. So if you have a DM that likes to steal your spellbook, he can't. Unless he curses you with amnesia...
The other options are Aligned Spellcaster (cast neutral spells as good spells etc. - only worth if you have alignment-based DC boost shenanigans), Disciple of Boccob (crafting at +1 CL for free) and Beleaguered Spellcaster (If you take 3x your caster level in damage from a single attack, you get a free maximize or extend - useless because you'll be dead).