One of the best things we ever did at our place was rip up all the carpet and expose the floorboards. I could never go back to carpet.
A couple of things - replacing the decrepid section of fence in our backyard that didn't match the rest of the (nice) fence and ripping off the disgusting rotting mission brown driveway gates.
We recently installed some outdoor power points. Wish I'd done it years ago! So handy for plugging in electrical tools like the whipper snipper, powering lights, radios, etc as well as recharging cordless tools while you're working in the garden.
Not "years ago", but I just recently completed a small deck area, which extends from our alfresco and I have been out there just about every day working with various plants, using the bbq more and just sitting out there and relaxing.
As I said, not years ago, but we built and moved in 18 months ago and I wish we had made that alfresco area bigger back when it was being made.