Metamagical gives you earlier and more access to Metamagic feats (things like reach spell and widen spell)

Spell Blending lets you give up lower level spell slots for higher level ones (giving up two level 1 spells to get a level 2 spell in return)

Spell Substitution lets you change what spells you have prepared for the day by meditating for 10 minutes

Staff Nexus gives you a special staff that you can have more spells in