First of all: Why are most of the downloads on here *.rar files?

And second: Where can I find a program that can read them?

let me explain a little bit.

rar files is the same as zip files, which is known as the lzh files in Japan. It is a kind of compressed file type. You can use WinRAR to extract the files inside a rar file.

I tend to promote 7-zip. It's basically the same as WinRAR but free software (open source), it handles most formats (ZIP, CAB, RAR, GZIP and TAR, etc, etc.)

http://www.7-zip.org/

www.tugzip.com FTW!

http://izarc.org/
Also Freeware and fast, very fast.

Quote from joen :

www.tugzip.com FTW!

+1

Quote from red_wing_2121 :

First of all: Why are most of the downloads on here *.rar files?

How else would you like them? Most material is best compressed, RAR is a very popular format, compresses better than ZIP too (possibly the worst format still around, due to age).

People should start packing things in 7-zip's .7z, they offer better compression than rars.
I'd say, in general:
7-z > rar/bzip > pkzip2 > gzip