Scrypt coins are coins which were orignially designed to whitstand the pressure from ASICs. Examples are Litecoin and Feathercoin (and more recently conyecoin).
Scrypt is an algorithm which is supposed to be slow on FPGAs and ASICS (some ASICS are actually just built using several FPGA boards) as it uses a lot of memory during hashing. At the moment you will notice that there are no scrypt ASICS yet! I know Alfa Technology has "announced" that they are building one, but it's currently still at drawing board level. Some people on Reddit are even claiming it might be a scam.
In regards to your question about 64 bit processors, it's not hard, it's actually quite simple. SHA-512 suffers from the same problem in regards to ASICs as SHA-256 did. Some people already decided to implement a crypto coin using SHA-3 (which is even FASTER than bitcoin is now).
In my opinion it's going to be a cat and mouse game, people are going to come up with a hashing algorithm and some other people are going to try and make an FPGA effective version of it. They will probably have difficulties at first, but at some point it might succeed actually.
I also agree with Terry's comment:
Also, designing a new cryptocurrency. Not a good idea when you don't
even have rudimentary knowledge of cryptography.