Java 7 update 51 brings us doomsday for unsigned and self-signed applets.
It’s been on the horizon for 6 months or so, but it’s here.
The cheapest route I found to buy a trusted certificate is from Tucows,
https://author.tucows.com/. Don’t mess around trying to create a company name,
just get a personal certificate.
If you don’t have the time or inclination to wade through the signing morass, please
remove your java applets. It will look bad for you and for java if a lot of java applets
seem to be nonfunctional.