One of my colleagues has been pretty ill. As I understand it (and I'm the wrong sort of doctor), it's an acute illness, one they're likely to recover from over the summer, but for now, it's been a rough go.
We do this "fill in" thing around here if someone's going to be away or gets sick. (I've written about it here.) If you're able, you send an email to the department list and ask for someone to fill in for these classes on this day, with a short comment about what they'd need to do. And usually, if things are planned ahead, people can arrange something another faculty member can fill in for.
When it's tougher, you contact the department chair, or have a loved one contact the department chair, saying that you're ill, and then the department chair takes over.
Since our basic load is 11 credits (over 3 courses), usually 1 writing course (about half the load), a lower level area course, and an upper level area course, that's a lot of courses to get filled in.
Where possible, of course, colleagues in the area help with the area courses, and the writing course can be filled in for with just about anyone who has the hour free and is willing.
At any rate, I'm now on my second week covering one of the courses. Another colleague took the first week, and then passed it along to me. I could pass it back, but it's Shakespeare, and a play I'm good at and love, and did I mention, Shakespeare? Yes. And I don't have to grade (at least not so far), and I didn't have to try to plan out the whole semester. So basically I go in for 3 hours a week and work with students on understanding Shakespeare. It takes maybe half an hour to prep for each hour, just to make sure I've got line numbers and such. (And filling in for one course means I feel absolutely no guilt that I don't think about the others.)
It's seriously the best way to teach ever. Just the fun part of talking about Shakespeare, and not the hard parts of organizing or grading. I could do this a lot.
(Let me say, I think my academic life would be a whole lot better if I were in a place where I taught an equal or slightly greater course load but all in my field instead of having my energies sapped by teaching first year writing.)
I wonder how many other departments or schools practice some sort of filling in for ill or absent colleagues?
On the other hand, filling in like this makes you realize just how selectively some of your colleagues arrange their courses to make rather minimal work for everyone involved.