theZoo's allows the study of malware and enable people who are interested in malware analysis to have access to live malware, analyse the ways they operate, and maybe even enable advanced and savvy people to block specific malware within their own environment.
I recommend running them in a VM which has no internet connection (or an internal virtual network if you must) and without guest additions or any equivalents. Some of them are worms and will automatically try to spread out. Running them unconstrained means that you will infect yourself or others with vicious and dangerous malware!!!