I have been into them since I was a child and received a small ambulance that took 10 minutes to assemble (well, I was 5).
I got my first LEGO® Technic™ (8818-1: Dune Buggy) set when I was 11 and it came with a subscription for a LEGO® magazine to which I promptly applied. I kept up to speed with all the new sets and collected a lot of them.
Back then, I had these (to name a few):
8448-1: Super Street Sensation (Enhanced by the motor from 3804-1: Robotics Invention System V2.0)
8431-1: Pneumatic Crane Truck (My favorite back then.)
8299-1: Search Sub
8858-1: Rebel Wrecker
8816-1: Off-Roader
8456-1: Fiber Optic Multi Set
8222-1: VTOL
And of course many more I can’t remember.
Then I moved overseas, leaving it all behind in America.
I never lost my interest but I could never really buy any because I had no stable place to put them; I was constantly moving to new apartments and even to new countries, and LEGO®’s are not a happy thing to pack.
So I waited about 10 years to restart my collection and I finally found a stable place to put them so that even if I change apartments/condos I don’t have to pack them up: My office desk.
Here is both my office desk and my current LEGO® collection (note that I do still have the sets from my childhood, although they are in America and I am in Japan).

Those headphones came from Thailand.
Here we have the:
9397-1: Logging Truck
8070-1: Super Car
9398-1: 4x4 Crawler
Some バタピー Peanuts.
Not shown, but is in the mail (will arrive any day soon) is the 8674-1: Ferrari F1 Racer 1:8.

Not sure yet where I will put it but I am eager to put it together. Funny how it is worth more than the iPhone 5, iPad Mini, and iPad 4 sitting on my desk (not combined, individually).
Today a coworker asked me why I collect these sets. My answer was simple: I don’t wanna grow up; I’m a Toys‘R’Us kid.
Who else has a collection to share? Or any custom-built sets? Don’t be shy.
L. Spiro