PS2 slim / pi2 SMB
Like everyone has done before I had an extra raspberry pi 2b laying around I wasn't using. Decided to set it up as a little samba share and it just works. Easy. I just really hated the look of it sitting on my shelf. So, since I have about a dozen ps2 7900x from building super slims I decided to take one of the ones I have with a dead DVD drive and just replace it with a pi. Simple power converter coming from the backside of the main fuse gives it constant power as long as the PS2 power block is plugged in. Set up a 512gb SD card with diet pi and reduced it to basically nothing. Only really running the samba share and nothing else. Booting takes all of 4-5 seconds and is incredibly stable. Obviously had to trim the case to expose the ports on the pi but it fits otherwise. Then the connection is between the pi and PS2 network ports. If I want to add games, just plug into the pi with a laptop and push them to the share.
I know, this isn't the perfect solution for everyone but I wanted minimal footprint and expandable storage. Only thing I had to buy was the power converter which was like $4 for 10. Works great. Highly recommend