+1 That's a great point to make for people who are building side projects. Make sure you list your side projects in an exception in the IP clauses of your employment contract, like I did.
Out of curiousity, what does that typically look like? Named project + brief description + market it's in?
Have you ever had any pushback from legal? Presumably to the effect of "What if you take our IP and put it into that project?"