Some sort of ice climbing simulator thing (Plice).
A place to run around outside.
Rings, both Rock Rings and gymnastic rings, place to hang 'em.
Some weight and a bar. A stylie set of Olympic bumper plate weights would be nice, but I've got a bunch of weights we got at garage sales for pennies. They work fine.
Anything after this is gravy. Really. Exercise balls, machines, etc. etc. are somewhere between comfortable accessories and shiny garbage. It's nice to have a squat rack and stands and so on, but it's not necessary. I go work out with my friends down at Athletic Evolution when I want the comfortable gear or a controlled environment (or for fun, good people), but you don't really need anything more than a jungle gym at a kid's playground and a rock. Or a tire.... There are a ton of wicked workouts here that don't require any gear at all.
I figure that about 90 percent of the machinery in the average health club is wasted space. Movements should be done as you do them in real life. A squat is not composed of a quad extension and a hamstring machine, it's a movement that involves just about every single muscle in your body working together. I generally reject Crossfit T-shirt slogans (you shouldn't wear T shirts with bad-ass statements on them unless you're a bad ass) in general, but "machines are the enemy" is a good one.
Anyhow, I had a long discussion with a guy on a flight the other day about all the junk in gyms (he was convinced a lat machine was better than a pullup), and it bothered me so you get to read about it. The most ubiqitous POS in the gyms I visit while traveling (and I do visit 'em even if I can barely see the micro free weight area over the sea of machines) is the exercise ball. Exercise balls should only be used for rolling target practice at 200 yards. Want to involve some more muscles in a situp? Do a front lever or a knees to elbows or a windshield wiper or whatever. If you can't do that then sit on the floor and try to balance on your own butt while picking your feet up. Anything can be scaled. Rolling around on a ball is only extremely useful for sports that require rolling around on a ball. Are you working out to get stronger in a useful way or working out to get better at rolling around on a ball?
But rolling around on a ball is better than rolling around on a couch for sure, so right on if you find it fun to get your ball on...
Now on to "core strength" as it relates to climbing and balls. I often get into discussions with people who think their "core" is weak for climbing. They usually can't get or keep their feet on an overhanging wall. Most "trainers" will prescribe rolling around on a ball like a spastic to increase "core strength." The ability to get your feet on a wall while climbing is NOT determined by your abs or anything having to do with that ball anymore than your ability to do a squat is determined by hamstring curls. To put your feet on the wall you need to be able to do just that motion--hang on two holds, swing up and place your feet and hold them there. You need more shoulder strength and front-lever style training than anything else. You could have the abs of a ball exerciser and not be able to do shit about getting your feet on the wall because, like the hamstring curler, the whole system has to work together. The shoulders, not the abs, are almost always the weak link. If I see one more "core" exercise for climbing that does nothing for actually climbing I'm going to burn the magazine I see it in on the spot. At least I'll be able to work out in my jail cell.
I had coffee with a good bud of mine, Greg from Crossfit Canmore, yesterday, and he made an interesting point that deadlifts improve his "body tension." I had to think about this for a minute, but he's right. If you've ever done a lot of steep-wall training for climbing or deadlifting you'll notice that your hamstrings and lower back muscles (not joints or ligaments, muscle) will be sore the next day. Front lever training gets your feet on the wall, but holding them there takes a combination of dead-lift hamstring/back contraction (and every other muscle involved in that motion) and shoulder tension. If you had bomber footholds you wouldn't even need any shoulder strength once your feet were on the wall, it's all back and legs. Many good rock climbers I've trained with are disproportionately strong on their deadlifts; I think this is because they have strong body tension and REAL "core" strength.
My measures of "strong" core strength would be this:
-Can do 15 knees to elbows in row (and not swinging spastic knees to elbows, controlled leg lifts), or hold a half-front lever for 10 seconds.
-Can deadlift 1.5 times bodyweight.
Anyone who can do that is not in general going to have any problem with "core strength" or body tension in life or while climbing. Very steep routes or tougher forms of life may require more than that.
So, if you're a climber that has a hard time holding your feet on the wall practice by hanging onto two good holds in a roof and swinging your feet up and "catching" holds with them, repeat with holds to the side, etc. The good news is that this strength does come relatively quickly compared to pullups or something. Some deadlifts may also help, as will knees to elbows etc.
Send your used exercise balls to me, I'll take good care of them.