Try Midwest Grill on Cambridge Street in Cambridge (just east of Inman Square).
Or you can venture out to Southborough (about 45 minutes west of Boston) for Ipanema Restaurant,
106 Southville Road.
I'm guessing that there are others, but these are the only two that I am aware of.
There's also Cafe Belo. One on Brighton Ave in a strip mall next to Dunkin' Donuts and Osco Drug. One in Somerville just outside of Union Square heading towards Sullivan Station (Somerville Ave, perhaps?) And they just opened a Cafe Belo Express - which I have not visited - on Somerville Ave in Union Square just across from the Market Basket.
It's all cafeteria / buffet style Brazilian food that you pay by the pound. At the end of the buffet is every rotisserie meat you could ask for - chicken, chorizo, pork, beef, as well as fish and some organ meats (like chicken livers.) It's also a great deal - you can eat your fill for under $10.
Funny you ask, since my wife and I just had lunch at the Rio Cafe out in Maynard.
Maynard? Apparently rents are cheaper out there and a few ethnic places are openinging.
Had the Rodizio (sp?) -- buffet table with cold salads and hot dishes -- fried plantains, black beans, rice, noodle casserole and a meat stew -- along with an endless procession of rotisseried meats. Kielbasa, chiken wings, bites of chicken breast wrapped in bacon, beef, spicy sausage, lamb, chorizo, pork loin. I think about that point we surrendered. Lunch price was 12.95 per person. You could also get buffet and meat by the pound.
They also had Brazilian pizzas on the menu which presented some unusual selections (I remember one having corn, olives, kielbasa, tomatoes, cheese, and several other things on it.)
Food was good, but I haven't compared it to the choices closer in.
David "Zeb" Cook