Hey, I'm japhy, and I've had LEGO sets for over 15 years, but it's only now that I've started making my own constructions.
My LEGO inventory is not nearly as massive as those of a lot of the other contributors I've seen, but I have enough to produce medium-sized castles and other buildings. From the LEGO sets I've accrued over time, I now have put together, from scratch:
Black Falcon's Fortress
Black Monarch's Castle
I've also created the following:
King's Tower Outpost
I also own most of the new Knight's Kingdom sets.
I have over 100 figures that I've broken down into several groups. I've recycled the new Knight figures; I'm not too keen on the color-coded armor and swords.
King's faction (new-style Lion shields)
Prince's faction (old-style Lion shields and new Red Lion/Bear shields)
Black Falcon's faction (Blue and Yellow Falcon shields and new blue Falcon shields)
Forestmen's faction (Deer shields and new green Monkey shields)
Wolfpack (Wolf shields and new purple Wolf shields)