I've been using iRows, which is a free online service for creating and storing spreadsheets, to store some spreadsheets so that I can access the information from any system with a web browser. However, I've found that, though the service works fine with Firefox, it is not usable with Opera 8.54. With Opera 8.54, when you try to save a spreadsheet, edit tags, etc. windows open behind the spreadsheet you are working on and it isn't possible to fully access them. I've been able to drag some of the windows to areas on the screen where I can access part of them, but I would not consider the service usable with Opera.
When I checked the FAQ at the iRows website, I found a statement indicating that iRows doesn't work well with the beta 9 version of Opera either. The FAQ states "On Opera-9 not all features work well. We are waiting for Opera to fix a few issues in the beta version."