I hope this thread will get plenty of "nothing - had a great and relaxing day" sorts of responses, because after all, interesting could be either good or bad.
For me, so far today, it would be making up a bunch of intraocular antibiotic injections. Now, the eye injections use different concentrations of the drug than the concentrations for the same drug if used intravenously. And the doctors wanted a different concentration than the normal one we use for the intraocular, so we could not use out compounding cheat sheets.
So my pharmacist had to play with the math for about an hour to figure everything out so I could make them. 
But they are interesting to make. You reconstitute the drug with sterile water, then pull up part of the solution in the vial in a syringe and qs with water to make the new concentration. Then pull part of the drug from the syrings into another syringe and qs again with more sterile water to get you final concentrations. And you have to be super careful not to even potentially contaminate anything because it is being shot into someone's eye. 
So, so far, that was the most interesting thing I have done today.
Brrrrrrrrrrrr! 
And maybe now you can have time to read 
