Going through the game again, and I found a few extra drinks your Mixologist may learn (especially if they are a high enough level). However, these require one of the earlier supernatural types.
You have to be at a Vampire Lounge to serve this, and your customer has to be a vampire. (It helps if you control two sims: One the Mixologist, the other customer)
Red Water
Plasma Punch
Sanguine Slush
As I submitted a while back on the main page:
Vampire: Hemoglobin Shooter
Robot: Oil Coolada
Mummy: Preservative Punch
Note: The vampire/robot/mummy may request these three at any bar, and a Mixologist may therefore learn them.
As LaBlue0314 first reported, the mummies also have two more special drinks, and these two can only be learned at a Vampire Lounge.
Dissolved Sand
Rehydrant
Of course, once a Mixologist learns any of these, the drink may be made at home, etc...
