A professional and responsible website should always offers HTTPS protocol to their visitors. The use of HTTPS (Hypertext Transfer Protocol Secure) will encrypt every data passed through its protocol.Username, password, and other credentials will be encrypted before sent to the web server. This would prevent the data from being easily hijacked.
But the fact, not so many website offered high-level security to its visitors, considering the access speed to the server will be reduced with encryption proccess.
Fortunately, websites who deal with financial information such as PayPal, implemented HTTPS in their server. I can see that Rapidshare is also using it.
But not all websites offered HTTPS protocol. Many large websites who stored visitors credential data didn't bother to care about the safety of their visitors data.
So, if you concern about the security of your credential data, make sure you have encryption all the time when entering username or password on a web page.
If the website doesn't offer HTTPS protocol, you can use a plugin from Firefox. This plugin makes sure all the data sent to the server will be encrypted through HTTPS tunnel all the time.
Although it doesn't work on all sites, it has been tested and working well on some major sites. Ironically, the the plugin doesn't have author name on it. So it's a bit suspicious.
The choice comes back to you, whether to use it or not.
Download the plugin here:
https://www.eff.org/files/https-everywhere-latest.xpi
