Posted a small plugin to GitHub for setting up a global subsite menu in WordPress multisite.
Basically, if you have a multisite WordPress install and you want to create a global menu with some or all of your subsites and show which subsite you’re on, this will help you build that menu.
It doesn’t have many features, and it has a lot of limitations. But I put quite a few filters in it so you can in theory make it do exactly what you need it to.
I’m calling it Network Subsite Menu and I uploaded it to GitHub on the off chance someone else finds it useful.