I like having my butt played with.
"Would you like a finger inserted?"
Generally yes. My wife's finger is the best, of course, but I can enjoy mine as well (as long as I'm not sore or having to concentrate too much on what I'm doing with it).
"A butt plug?"
Tried that, it can be fun both during sex and as foreplay.
"An enema?"
I guess I can say yes now. I didn't used to enjoy them, and many times now they're still more utilitarian than fun (IBS-C), but sometimes they're fun. I guess that a big reason I considered them for "practical" use was that I was already OK with playing with my anus, so the "eww" factor was not there. Recently I've been playing around a bit more, giving myself more time for them, longer and more sensual injections, and they're becoming more enjoyable.
"Dildo?"
Haven't done it as much, but it can be fun. Using one at the current time for prostate massage due to prostatitis, hope to continue with toys and fingers afterwards for fun and possible health benefits.
"Strap-on?"
Haven't done this, but would consider it with my wife.