I keep making Browserling easier to use and I just released an Opera add-on for Browserling. This add-on lets you quickly access all the platforms and browsers with one click. No need to go to browserling.com first to start cross-browser testing. Just install the addon and you're ready to go.
Try it out now and let me know what you think!
In the next few months I'll also be releasing addons/extensions for Firefox, Safari, and IE. I already released Browserling's extension for Chrome two months ago.