In addition to the Märklin track and the Micro Trains roadbed track, the English firm Peco manufactures flex track and rail joiners for Z-Scale. In recent years, the Japanese firm Rokuhan has also added a line of track products which include wider radii curves and other useful sections.
For those using the Märklin track, IBL manufactures cork roadbed elements for Z-Scale. These pieces are useful when using the Woodland Scenics Terrain System; the roadbed is hot glued onto the track risers of this system, and the Märklin track is attached to the roadbed pieces. IBL is also a source for the manufactured layout forms discussed here.
As an aside, I also have a good number of IBL display cases that hold my train and toy collection; they’re well built and attractive.