JRE for Firefox on Debian/Ubuntu?

I had problems viewing Java content in my Mozilla-firefox that came with Ubuntu. Tried tweaking myself, but all invain.

Found this page very helpful, could not find email address to thank the author.

UPDATE: Found that Jeriko’s blog no longer contains that info, hence I am editing my post so that others could get benefited.

Mozdev’s soln

Gentoo-wiki’s soln (works for any distro)