I work at a very small business. My personal laptop is my development environment along with the desktop I have at home. My development environment is pretty much whatever I want it to be, so I don't feel limited like i have at other employers. I'm in charge of all the tech at the job, so I do whatever I want.
The boss is an inventor, so he actively encourages me to try new technologies and learn whatever I think would be fun to learn. It's cut down on how much I do at home and has allowed me to actually delve into my other interest areas outside of programming. I still do spurts of it here and there a month at a time, but this job allows me to look into new technologies without feeling like I need to do job training at home too.
Sometimes I get excited about work and do a lot of it in my free time, but sometimes I get excited about stuff I do at home and then do it at work too. For this job, I'm fine mixing "church and state," but I've had other ones were 5:00 hits and it's fuck you all; you're not getting a damn cent of value out of me past this point.
I've always liked the google 20% policy. You get time to do stuff out of the monotony. It helps generate new ideas while also introducing you to new tech.