There was only one place I didn't have to do that -- Netflix. It's part of their standard agreement. It even went one step further and said that even if you use their resources, if you do it on your own time you own it, as long as it's not in direct competition with their business. It was a refreshing change for sure.
My current company has this exact policy. It's one of the many reasons I enjoy working there so much. :)
I blacked out all the parts that change based on the company, because I'm not sure how much I was allowed to share.
The list of inventions is basically and thing or idea you had that you might want to work on. It's a good place to list any open source projects as well as any ideas you might be working on for a company.
Turning it around, it would be pretty much untenable if employees could file their own parents on work-related inventions done on company time with company equipment.
Exactly how far "related to your job" extends is up for debate. Because of that, I have an additional clause in my employment contract that specifically states that any contribution I write to FOSS projects is mine to license and distribute.
I feel your pain. It's bad enough that the company that holds the patent isn't using it, but you can't use it in future employment. I'll always have this nagging desire to just do it the easy/awesome way, but that's off limits now. The money they give to get a patent isn't worth the roadblock you create for yourself down the road.
In no way am I defending the current state of IP or patent law in the US (on the contrary, I would prefer abolishing all patent law over the current system). However, it's definitely not impossible to learn things from patents.
Serious question: How could you know that?
(Someone could have re-discovered those ideas independently and/or your past employers may not spend effort to identify infringement.)