There are a number of ways to go about doing it. I'll tell you how I do it. It is a kind of sharing, not really sharing all of /home.
I use a separate /home for each distribution because of the different config files, set-ups, and desktops used for various distros. I have one machine that I use to play with lots of various distros that of course changes as the mood strikes me. I usually only give about 2 Gig each to the /Home partitions on this machine. Really I don't need to even put /home on a seperate partition doing it this way, but old habits die hard.
My user name is "fred" on all the distros, surprise surprise.
I create a folder in /home called "data". This folder is mounted on a separate 30 Gig. partition as /home/fred/data/. This partition has all my documents, music, pictures, and other misc. junk in it.
So when I put a new distro on the computer I just create a folder in home and mount it in /etc/fstab. That way regardless of which distro I am using at the time all my data is accessible in /home of that distro.
I guess you would call that a compromise, but I do it so I can see the way each distro is configured out of the box before being tampered with. It also makes it practical to share, some what, between very different kinds of distros.
Hope this gives you some ideas.