StumbleUpon is a great service to discover new site and share it with like minded people. StumbleUpon makes it easier for users to stumble upon or share sites by providing a toolbar to users, unfortunately the toolbar is available for only Firefox and IE users.

Stumbling becomes harder for users who use Opera, since it involves manually loading stumbleupon.com and reviewing the site or giving a thumbs up to it. We shared the same annoyance as other StumbleUpon Opera users faced, since we had to toggle between Opera and Firefox to stumble a site, this led us to search for a tool that would make stumbling from Opera much more easier.

Related: Run Greasemonkey scripts in IE, Opera and Safari

OperaStumbler is a great alternative of the StumbleUpon toolbar for Opera users, they provide you with 4 different ways in which you can use StumbleUpon with Opera;

We prefer using the Menu Version for ease of access and ability to have all the SU toolbar features.

You will require to provide your stumbleupon details before you can start using OperaStumbler, but once you are setup, there is no stopping you from stumbling websites in Opera.