When selecting a date and time for adding items to your calendar, the slider is in 1 minute increments and there are no graduated markings next to the slider to tell where to stop for 15, 30, 45, etc. I mostly put things in my calendar in 30 minute increments, and sometimes in 15 or 10 minute increments, but never more granularly (new word?) than 5 minute increments.

1) add an option for 5 minute increments (and maybe 10 or 15).
2) add graduated minute markings.

If Simpleology could read the data from my Google calendar, it could shade the areas next to the hour slider which are already booked for the day I have selected.