plagren: The plural is "forums". You're speaking English, not Greek or Latin. And if you insist on using plural forms of other languages, why restrict it to those two?
Because that's generally how it works. The "proper" plural is from Latin, there are other accepted plurals that were mostly used by the uneducated that are becoming more common. However, strictly speaking, the plurals historically came from those respective languages.
It's hardly my fault that the spelling system was developed the way that it was. We primarily restrict it to Latin and Greek for the simple reason that the people who wrote the first dictionaries of English were educated to read and write those languages. They were also languages that were still being used for academic writings.
These days, the standards have been somewhat relaxed so that people will use either set, but in a strictly technical sense, the Latin and Greek plural forms are more correct.
EDIT: If we're being technical, there's a small number of others that have snuck in from one language or another. Oxen is a fairly good example. We have Ox and Oxen, but generally not Box and Boxen. Although the later appears occasionally in some contexts when people are either non-native speakers or being cute. In many cases the rules about plurals have been reduced to a rote memorization of spellings.
hedwards: multiple mass exoduses
Vainamoinen: Exodi.
I AM JUST KIDDING. It's too hot folks. Losing your cool over latin vs. English declension, simple corporate apologies or positive experiences with DRM, it's not worth it. It's just not worth it.
Touche