Brazilian -- There are a few churrascurias around; the all-you-can-eat meatfest became popular during the Atkins fad.
Fogo E Brasa in Ahwatukee is popular. I've also heard about a simpler, non-churrascuria Brazilian restaurant in Goodyear called
Val's, but I also heard it closed. Call before visiting.
Greek -- Local chain
My Big Fat Greek Restaurant wins the prize for silliest name and fastest expansion. Some people like it, but I'm not a big fan. My favorite is
GreekTown in Sunnyslope.
Vietnamese -- Too many to mention. The biggest clusters of Vietnamese food are on the west side, particularly along 19th, 35th, and 43rd Avenues and along Dobson Road in Chandler and Mesa. There are many others scattered throughout the metro area. My current favorites include Khai Hoan and Pho Mesa, but there are many good ones. You may want to check out
Mekong Plaza, a shopping center with a southeast Asian theme that just opened at Dobson and Main in west Mesa. Once all the stores are open, it will house several Vietnamese restaurants in one plaza.
German -- There are a few scattered around the area. My favorite place for German is a strip mall in east Mesa that houses two restaurants:
Zur Kate and Bavarian Point. I don't get there much, though, because it's so far from me. There's also
Haus Murphy's in Downtown Glendale and German Corner in Arcadia.
Filipino -- Filipino restaurants come and go but don't gain much traction here. I'm not up-to-date on where the good ones are right now, but I'm sure there are a few out there.