I was thinking about a way how to easily find a bookmark or note I have stored in Diigo from the Opera browser. I wanted to have something like the official Diigo Sidebar which is available for Internet Explorer or Firefox. But it won’t be that easy to implement.
Suddenly I got an idea to have this access through Opera Search bar. So I just created custom Search engine in Opera which searches through my Diigo Library.

Put some custom name for the search engine and keyword which is used when you want to search using this Search engine from the Address bar in Opera and the engine is not set as default.
The address is following: http://www.diigo.com/search/my?q=%s
Thats all, enjoy it