Opera

If you can't get a plug-in to work, you may still be able to open the file from Opera.

Go to Tools > Preferences > Advanced > Downloads, and locate the correct file extension for the type of file you wish to open. Select it and click "Edit".

Use the the "Open with other application" option, then click the "Choose" button and find the application you want to handle this file type.

This will allow you to take advantage of many of the same capabilities that plug-ins provide. Examples of external applications that can be used are Adobe Reader (Acrobat) for the file type application/pdf (file extension: pdf), or Real Player for video and audio.