So, I'm planning to buy an arduino for interfacing with a shift register IC (4014). I want to use it in my Modellrailroad to check there a train stands or not. The shematic and a description of s88 (it's called so) is on this side: Paco's Official Web Site. How can I interface with this shift register and do I need any additinal parts between the shematic and the arduino? Even if somebody has a lib to interface with shift registers like what I would be greatful.
JanD
Yes this looks like it will work. However the schematic is for the 4044 shift register and not the 4014 you are using so check the data sheets to see if they are pin compatible. My only gripe is that I would put 0.1uF supply decoupling capacitors on every other chip.
Shift registers can be assessed with the shiftOut() and shiftIn() functions there is no need for a library.
Actually Mike, the schematic reads the 4044 latches (Q output levels) into the inputs of the Parallel-In Serial Out Shift registers (4014).
Using the Shift Register examples as a guide should be all you need to research.
Also... some good background info on SPI (this type of interfacing) is here as well:
the schematic reads the 4044 latches (Q output levels) into the inputs of the Parallel-In Serial Out Shift registers (4014).
Ah yes, forgot that those shift registers didn't contain their own latches. New fanged CMOS, I am more of a TTL man myself. 
Is it for even the 4014? or just the 4021?
between, does any one know a schematic to transform the 5V from the arduino to +20V/-20V (called booster) that is needed to contol digital modellrailroads?
For DCCBooster schematic, my preference would be:
http://home.cogeco.ca/~rpaisley4/MyDCC.html
Scroll down a bit and you will see th Booster Schematic based on the LMD18200.
Thanks for the site with the booster, but I have still not got an answer on my question if it works in the same way for the 4014 like for the 4021. On the arduino homepage it only reads about the 4021.
Jan