Web proxies and VPN's are used for all sorts of reasons, most important of these is anonymity. If you are Anonymous online you don't have to worry about others finding out what you're up to and you can feel more comfortable doing tasks such as whistleblowing. VPN Subscription's are, basically, proxy programs. Instead of connecting to the proxy server via websites however, you connect via a program running on your machine.
Another reason why someone may want to use a proxy is if your work or school computers block access to websites such as facebook, google, youtube etc.. A web proxy and VPN's will allow you to access these blocked websites, so long as the proxy/vpn server's IP isn't also blocked. Proxies are well known to show alot of ads, but we're not! - we want to show the least amount of ads as we can and still make a profit. We achieve this by using adsense on our home page only and show no surfing ads to our users. The way we see it, if you give people a great website they will come back and share the website with their friends, so in the long run we believe we will still make money by not flooding the whole website with adverts. :)