Greetings, all!
I'm aware of Complete Arcane's feat Obtain Familiar. I'm aware that a familiar isn't a feat for the classes that get it (Sor/Wiz, some others), but it can be traded for alternate class features (like Abrupt Jaunt) as if it were a feat.
These are my current revisions to making a familiar useful.
1: Full summonling benefits! I treat a familiar like any other summoned creature. (The Sor/Wiz ability is called "Summon Familiar." If your familiar dies, you can summon another one later. You may use Summon Familiar once per 24 hours, and each summoned familiar has a duration of 24 hours.
Also, since a familiar is summoned, it's affected by Augment Summoning and all other abilities which affect summons.
2: HD scaling and feats a la psicrystals! Psicrystals get real, actual HD as their masters gain levels in the appropriate classes. This grants them feats. Mind you, they can't get much in terms of feats, but it's something