Minihome

Courtesy of Jonathan Jacobus.

HMS Dreadnought

Great cutaway of boiler room C from John Robert's "The Battleship Dreadnought,"

Via Daryl Carpenter. 

See here to look at the original with the annotations.

Bus Hotel

Great section from architect Aristide Antonas.

HMS Belfast Circulation

A great diagram from Ciaran Hughes.

How Long Do Animals Live

An info-graphic from the 30's Otto Neurath.

Courtesy of Ciaran Hughes.

Nuclear Reactor Cutaway

It's kind of funny how sections are handled for the non-engineer/architects - it's more like walls are chipped away them completely removed.

Courtesy of Paul K at BibliOdyssey.