Have any of you ever tried an ab wheel? They look great because of how they work your abs, obviously, but I'm more interested in what they can do for my arms/shoulders/back! I'm checking them out on Amazon and they're only like ten bucks so I might give it a go anyway, just wondering if there's any reason I shouldn't bother

Ab wheels are great, go for it.

I have an old Ab Wheel Glider (I got it right when they came out). I use it a couple times a week and love it. If you can find one (any brand/type) and want one, I'd say go for it! The only downfall for me, personally (now anyway) is most of my house is carpet now. I found it much easier to use on hardwood floors. The carpet just gives more resistance, which can be a good thing, depends on you. That's the only "flaw" I can think of and it's not really a flaw, just personal preference lol.

Ab wheels are great, unless you have lower back issues like I do. For that reason, I bought an Ab Rocket. This is a spring-loaded chair type machine that helps you through the situp process. I can and do use the Ab Rocket everyday, and it works great for me.