I can accept proxy sites if it is of quality. You can submit it to the following categories: http://www.directorypro.biz/Internet/Security/ http://www.mishre.com/Computers_Internet/Security/ http://www.emporium-directory.com/Internet_Services/Security/
If you site is full of adsense ads, many directories will not accept them. You can submit here if you meet guidelines http://www.bqtm.com/computers_and_internet/security_and_encryption/
I would recommend checking a proxy sites robots.txt file to make sure they are not an easy target for 302 hijacking.