Thanks a lot for all the replies.

Quote Originally Posted by GavinRuneblade View Post
Adding to the list, some barbarians can cast rituals, and clerics too, then there are the people with dragonmarks, plus a boatload of non-WOTC-created classes you can find on DMSGuild.

In a practical sense, what I do is on the actions tab of a charactersheet add a category for rituals, then drag/drop the spells into it. As they don't use spell slots it doesn't matter what spell level the ritual is so they can all be lumped together in one place. The player can click the bar of the power to toggle it open/closed so it doesn't occupy any space if they don't want it to.

Attachment 26574 and Attachment 26575.
This sounds like a good solution. We will put it to the test.