I hate the term 'world' too. I hate the nationality lottery in music in general, actually. If you aren't from North America, Western Europe, Australia or New Zealand you won't get anywhere, no matter how innovative and/or talented you might be.
I mean, any band of ours who has any sort of mainstream success sells albums all over the world, yet how many Asian or South American groups get success over here?
Case in point- X Japan (should be obvious where they're from

). At worst, they are on par with 80's glam bands like Kiss and Twisted Sister in terms of talent. At best, they could match the big rock legends such as Led Zeppelin. In fact, their best song, Art of Life, has been compared to Stairway to Heaven.
But despite this, as well as the fact that they have made several serious attempts to crack the USA, often sing in English (and very well too, I may add) and have a bandleader who A) Is a total attention seeker, B) won't give up on anything he sets his mind on and C) Lives in LA- they still haven't broken through.
Yeah...there's something not quite right there...
Anyways... some my favourites in 'world'.
Finnish
Eramaan Viimeinen- Nightwish (with Jonsu from Indica on vox)
Chinese
Lunar Eclipse- Silver Ash (For starters.)
Japanese
Muma- the Nightmare- Buck Tick (You'll want the live version- it's amazing)
Ascendead Master- Versailles (Although there is 1 word of English in the chorus. Don't ask why

.)
Solitude- Moi Dix Mois
Gekka no Yasoukyoku- Malice Mizer (this is quite a strange song, though)
Metamorphose- Lareine
Hai no Yuki- Exist Trace
Also, I'll second any Rammstein suggestions you have. Slovenian band Laibach also have a few songs entirely in German, I believe.