I'm not aware of any builds for Opera of the G or Y toolbars.
You are able to add Yahoo's MyWeb 'save web page' button to Opera though, if you
* goto
http://myweb.yahoo.com/myweb/tools
* find the heading
Firefox/Safari Browsers:
Simply drag the link 'Save to My Web' to the Links toolbar in your browser.
* drag the link Save to My Web to Opera (e.g. the startbar).
This way you just have to press the new button and the javascript will open the default prompt to save pages to myweb.
You are probably aware of this, but in case not:
* You can add any search engine to the search engine dropdown list, by right clicking on the search box on any webpage and select add.
* Opera comes with ad blocking funcionality.
* Panels for Opera has lots of funcationality
http://my.opera.com/community/customize/panel/
There's some toolbar information below, but I'm not sure how relevant this is to your question?!
http://operawiki.info/WebDevToolbar
http://my.opera.com/community/forums/topic.dml?id=159695&page=1#comment1750644
Have fun!
Otto