Opera recently made their browser free for a couple of days as part of their 10-year anniversary party. At the time, I said I hoped they could find a way to make it free permanently, so it stood a chance of being taken seriously.
This has now happened! Opera 8.50 is completely free, and with no advertising banners. I’ll certainly be running it regularly as an alternative to Firefox, to see whether it stands up as a primary browser. I’ve also reconfigured it to “Identify as Opera” rather than as IE 6.0. I hope this will soon be the default setting, to ensure more accurate reporting in web stats.