self referencing

I noticed some games have little puns or a few easter eggs that are shout outs to the game's home system or something related to it's dev. team, sometimes to a source of inspiration or a potential sequel...

but how often? how many games do this, and how shamed should we be for using up all our concern points elsewhere?

I can't think of many off the top of my head but I can definitely confirm it happens. I can't think of a particular company that does it habitually so finding source material may take a bit. Next time I level up I'll be sure to invest some more concern points in this matter so I can dig up more information for you.

I think nintendo does this quite a bit- lets see... i think every installment of Mario and luigi (superstar saga, partners in time, bowser's inside story) had some character using the hand held the game on for some kind of scanning or communication device, ...
one of the treasures in the massive loot bag at the end of wario land 4 was a box of GBA's (a little unnerving it was the same model as mine...that absolutely had to be coincidental right?)
I know luigi's mansion had some kind of gameboy tool in it too.

aside from nintendo, i think Scribblenauts had a random teleport/time travel destination that could take you back to the beta testing lab...
these are just simple examples- most of the hints are far less obtuse and might even require some kind of obscure knowledge that people only notice when they're actively studying obscure knowledge.

Devil Survivor's "COMP" looked a lot like a DS. Additionally the 3DS remake ads some aesthetic changes such as the circle pad so the Overclocked COMP looked like a 3DS. That's all I can think of right now.