DDOS
Most of this text was just taken from the reddit post and formatted slightly. Enjoy!
Introducing a new rail system! The DRuNK Dialable Omnibus System.
Came up with this while playing with 1.8's redstone, thought people might like when they build their rails next rev. DDOS is a 8 track selector system that uses 1.8's new redstone mechanic involving item frames. Item frames generate a redstone signal with a strength of 1-8 depending on the position of the item. This allows for the creation of a simple 8 way dialer by placing signs with the destinations around the item frame.
To make use of the signal it is converted using two comparators in subtraction mod. Essentially the signal, x, is converted to 15-x-(x-1) or more succinctly 16-2x. The two spacing of the signal makes it perfect or a rail switching system as that is how far turns have to be from each other.
Technically any item can be used as the dial, but some are better visually than others. I like to use sugar because of its high contrast with the frame itself and the default position (signal strength = 1) is pointed straight up. If you prefer to use arrows then be sure to rotate all the signs so they line up with the arrows default to pointing to the top right corner.
Gallery
Click images for larger view
North or East facing overview
North or East facing redstone
North or East facing track switcher
DDOS Control Panel
South or West facing redstone
South or West facing track switcher
DDOS Control Panel
CARTS control Panel
CARTS redstone
CARTS track selection
Size comparison
Schematics
Not really complicated enough for schematica I think, but whatever, I made two real quick. Note: Schematica for 1.8 doesn't always (ever?) deal with item frames well, just put it in the middle of all the signs. Because of rail turn behave two slightly different designs are needed to accommodate the torches in certain directions.
Files: