I saw your email, and I'll personally send you an email when an Opera version is available. Given that Opera is just a fork of Chromium, you can actually install most Chrome extensions directly from the Chrome Webstore[1], although that's just a temporary fix. I plan on fully supporting Opera in the near future.
As to the business model, I certainly considered monetization while building the product, but my initial concern was just solving my own problem and getting Freezetab into the hands of users. Given how successful the launch was (it's the #1 product on Producthunt today[2]) I'm actively exploring monetization strategies.
Given how many requests there are for cross-platform availability, I think I'll set up an email list to notify everyone when it's available for Firefox and Opera. I'll update this thread accordingly.
[1] http://www.makeuseof.com/tag/how-to-install-google-chrome-ex...