I recently found out about "Land Paddling" and fell in love with it. You get on a longboard armbreaker skateboard and push yourself along with a Kahuna Big Stick, a lot like stand up paddle surfing.
I've done it a few times with a homemade push stick, a tennis ball on the end of a bamboo rod, which was pretty fun but not as effective as I wished. The tennis ball was eaten up pretty quickly, but the bamboo stick was light and stiff.
I ordered the Kahuna Big Stick for $89 and waited patiently for it to come. The difference it made was tremendous. The carbon rubber bottom and nicely shaped handle at the top was like adding icing to a cake.
The workout goes like this - You get a longboard skateboard and push yourself along. When going downhill, you swoop side to side like surfing, working your balance coordination like crazy. When on the flats, you "paddle", working your abs, lats, shoulders, arms, and forearms pretty nicely. When going uphill, you can pretty much triple the flat land workout.
When you put it all together, it's like surfing, casual flat water paddling, or intense white water "holy sh*t, look out for that rock!" paddling, depending on the amount of slope you are on at the moment. If you get up enough speed on a downhill, it can even be, "Holy sh*t! I'm going to die at Pipeline!" intense.
What's really nice is that you are actually going somewhere and it's as challenging as you make it, so you can put in an hour of land paddling and not even know it. I did 40 minutes of it last night and woke up today nicely sore and could definitely feel it during my swim. Sweet!
You will either need some prior skateboarding experience or a full body helmet for the first few days. If you're good with that, it is an awesome way to get in a great upper body and core workout while cruising around your neighborhood. I give it a big thumb's up.