Mark built a pirate harbor scene based off minifigures. The two buildings use some pretty interesting techniques, especially on the roofs.
Luke Lyons created an amazing modular university. The two story building took two years to complete and is modeled after the Academic Building at Texas A&M University.
Back in winter 2014 Boise Brick built the wonderful Eastlake Victorian Home. The architecture of the home features decorative roofs, lattices and windows.
betweenbrickwalls built the Calmwater Cliff House. The two story residence is situated in a cliff along a beach, which can be viewed from a terrace on either floor of the home.
This seemingly innocent house transforms into a mechanical behemoth. hiddenderek built the 1600 piece model which includes working arms, legs and an opening roof.
Ymarilego designed and built Granny's Bed & Breakfast, a charming old home run by a widow who's husband was lost at sea. The model has about 2800 pieces and you can learn more by visiting the design on LEGO Ideas.
Captain Braunsfeld built a series of old western theme buildings. I posted some of my favorite ones, which includes a saloon, bank and general store.
ThomasW created the Observatory Juno, named for the spacecraft to Jupiter. The three story building includes a mechanical dome that rotates and has doors that slide open.
Boise Brick modeled an old west store general, of which was common in the American southwest during the 19th and early 20th centuries. The second floor houses the owners of the store.
One of my favorite LEGO Ideas builders, Namirob, built and rendered an old winter museum. The three story building is nestled deep in a pine forest, and can be explored further by removing the modular floors.