.CON
Condensation Archive. Relies on slight shifts in the properties of magnetic media due to dampness. Instructs the write head of most hard drives to skip sectors at such a frequency that natural humidity condenses into water droplets on the disc surface. This allows data to be written with an 8% savings in storage space. Not recommended.

.ARF
Alternate Reality File. Does not compress; instead causes data to be written to storage media's counterpart in a parallel universe. Local file is a potentially worm-hole inducing version of user's data, brought here from a reality where all the information that has ever existed can be stored within about 3KB. So, some great space savings there.

.HYP
HypnoText. Small-footprint app displays swirling colors while flashing contents of text file. Data is stored in user's brain for retrieval upon hearing the trigger word "Kalamazoo!" Compression is variable and occurs when user scrunches up his or her forehead and envisions a tiny little dot getting smaller and smaller.

.TCOMP
Trash Compactor. Reduces space needed for items in the Trash/Recycling Bin by an astounding 100%.  TCOMP archives are unfortunately not retrievable.