I’d go on hundreds of fishing trips all over the world and attempt to set some line class records.
Having sex with many beautiful women.
Somebody mentioned polo in a recent thread, which piqued my interest. I’m going to look into it when I finish my actuarial exams. This will have a double advantage in that I will be making a bit more money, and I’ll have more time.
And if I play polo, people will think I make even more money! However, I may become a tedious wanker, reliving yesterday’s chukker to people who don’t give a horse dropping.
Well, money shouldn’t be the constraint. Go buy three lacrosse balls ($2 each), or three tennis balls ($1.99 total) that you fill with sand. Then do some googling to find plenty of websites with useful instruction.
You could also go the big-bucks route and spend $8 each for hand-sewn beanbag balls.
(Really - it’s one of the cheapest hobbies ever.)
Expanding my library and DVD collection, probably. Also get a really nice chess set.
A new hobby? All conceivable forms of karate, jiujitsu, kung fu, and taekwondo, use of the nunchucks and katana and shuriken. Ninja skills, baby. 
I would resume/restart my Kuk Sool Won training, until I got to at least 2nd degree.
I would take flying lessons. Get my pilots license.
I would have a 100 gal salt water tank. Maybe a reef tank.
I would buy and restore a GIGANTIC victorian, or possibly purchase land and do my best to build a Victorian style house from scratch.
Take up shooting seriously.
Well, I’d start scuba diving again. It was cheap and easy when I was living on the Mediterranean, a short hop from the Red Sea. But now that I’m living in Massachusetts, I have to fly halfway across the frickin’ planet if I want to get in any decent diving.
As for a new hobby–I’d love to take up skydiving. My wife gave me a sky dive for my birthday once and it was the most exhilarating thing I’ve ever experienced. Of course, that was when we were childless–now that we have a daughter, my wife’s all like, “You’re not allowed to die.” Wimmin! :mad:
Skydiving. Rock climbing. Scuba diving. An ultralight. Bungee jumping.
I’d also take many classes in electronics and buy much equipment and supplies.There are many projects I want to build.
I’d get a sewing machine and take some classes in that.
You get more mindblowingly awesome by the day! (Orange belt in shotokan karate and rising.)
If I had more money, I wouldn’t have settled for the ‘but we need a paycheck’ shyte job I have now. I would have waited until something in my field opened up.
And If I was rich, I’d make & jar 20 recipes of salsa I’ve come up with & sell them at craft fairs & flea markets. I’d do it & travel around the US just for the fun of doing it. And as long as she had money coming in, my wife wouldn’t much care where I was.
What I would like to do for a 4th of July display:
Load up 2 KC-135 tankers chock full of gas and and all that stuff that makes fireworks so colorful, fit them with remote piloting gear, and smash them head on into each other maybe 10,000 feet up and a couple of miles off the shore of Lake Michigan, with a HUGE audience of several million to watch.
I’m sure I could do this with just a little more money… maybe $20-30 million?
Hot air ballooning, I think.
2 chicks at the same time.
I’d like to spruce up the car a little, I sort of like the one I’ve got right now.
Oil painting. It appears to be the kind of hobby where it’s very easy to drop $200 in paint tubes and not have anything to show for it afterward. 
So many things…
Build a greenhouse room and have tea (camellia sinensis) trees, a meyer lemon and a lime tree… (I prefer to live in climates too cold for these lovely, fragrant trees)
Grow culinary and medicinal mushrooms. I’ve grown small tabletop blocks of shiitake, maitake, and lion’s mane, but it would be fun to go larger scale.
Get toe surgery so I could cross-country ski again.
Buy my own kayak and paddle far more often. Go on paddling trips in New Zealand! Hike the Milford Track in New Zealand. (That, also, after foot surgery.) Heck, just look at sheep and drink beer in New Zealand.
(My book and reading addicitons are already at the max.)
Improve my French via more frequent trips to Montreal.
I would sign up for Knitting Boot Camp.
From September to Marchish, regular knitting instructions with buttloads of homework.
Dead Sexy or whut?*
*As I always have on my proximity a pair of sharp pointy needles, the correct answer is “Dead Sexy”. TYVM.
Check …
… and check.
Actually, depending on how much more money we’re talking, I’d buy acreage with barns and housing and set up a horse retirement farm. There are quite a few horse rescue groups in the midwest, and I’d adopt all of the unrideable “pasture mates” they have (so they can use their resources towards more “adoptable” animals) and set them up for life. I’d have quite the collection of beautiful lawn ornaments to love, pet, groom, feed, and just enjoy being with. See, I don’t even have to ride horses to be happy … just being around them is enough for me!
And two chicks at the same time doesn’t have to cost a penny … you’ve just gotta know the right chicks! 
I would take up stained glass. The classes are a few hundred bucks but then there’s supplies and equipment.
Cocaine.
I got my pilot’s license 5 years ago, if I had the kind of money to spend $70 an hour giving friends rides I’d do it more often.