The agreements I've signed have been part of the contracts at the 3 engineering/design firms I've worked at: mindtribe.com, ideo.com, and greenmountainengineering.com. (I've also worked a few other places, but they were schools and an environmental foundation.) Actually, now that I think of it, the most aggressive agreement I've signed was when I was working as a researcher at a university robotics lab.
In all cases, the agreements had the list of exceptions you mentioned, but they only took ownership of stuff I thought of while I was on the clock. At the last company I worked for, the agreement was very contentious-- the employees lobbied for, and eventually received, an agreement that allowed them to own not only their off-the-clock ideas, but also their on-the-clock ideas if the company didn't develop them within 6 months. (There were more details, but that's the rough idea.)
At the time, I thought this was a big deal. In retrospect, I think all that stuff is just people making stuff up about what is going to happen in an imaginary future where ideas are worth millions and lawyers are free. All the same, I still refuse to sign agreements like that-- I think it distorts the way innovation actually works. As it's said, we're all standing on the shoulders of giants; I don't want to be under the control of someone who doesn't understand that.
In all cases, the agreements had the list of exceptions you mentioned, but they only took ownership of stuff I thought of while I was on the clock. At the last company I worked for, the agreement was very contentious-- the employees lobbied for, and eventually received, an agreement that allowed them to own not only their off-the-clock ideas, but also their on-the-clock ideas if the company didn't develop them within 6 months. (There were more details, but that's the rough idea.)
At the time, I thought this was a big deal. In retrospect, I think all that stuff is just people making stuff up about what is going to happen in an imaginary future where ideas are worth millions and lawyers are free. All the same, I still refuse to sign agreements like that-- I think it distorts the way innovation actually works. As it's said, we're all standing on the shoulders of giants; I don't want to be under the control of someone who doesn't understand that.