Currently I have an R4i (or whatever, it's a DS flashcard I use in my 3DS to play DS games), I also have an old R4 card that's in my DS (only ever used when it's a game that needs the GBA slot for an accessory, which is the paddle controller, that's my only reason to ever power on my DS, but what a good reason, that should have never gone out of style, that type of controller should still be around, and if you don't know about it (I didn't, I just got it because I love useless accessories) it's close to the best thing that ever happened to gaming, plenty of concepts being possible apart from pong, space invaders and puzzle bobble.
I also have an EverDrive for my Famicom... That's it, I hardly ever play anything else, I have loads of other consoles though (most with HDDs) I just never return to them and see no reason to connect them to the TV or power grid.
I used to have a flash cart for my GBA, before that I don't think they existed, don't know what happened to it, but the handheld broke, so I probably gave it away. Those were good times.