Arby's—the enunciation of the acronym of it's signature food- roast beef, or RB, thus Arby's.
Hotmail—Founder Jack Smith got the idea of accessing e-mail via the web from a computer anywhere in the world. When Sabeer Bhatia came up with the business plan for the mail service, he tried all kinds of names ending in 'mail' and finally settled for hotmail as it included the letters "html"—the markup language used to write web pages. It was initially referred to as HoTMaiL with selective upper casing. (If you click on Hotmail's 'mail' tab, you will still find "HoTMaiL" in the URL.)
Nintendo—Nintendo is composed of 3 Japanese Kanji characters, Nin-ten-do the first two of which can be translated to "Heaven blesses hard work"; do is a common ending for any store.