CBC Sports (eh?) via Baseball News Blog reports that the Toronto Blue Jays, as early as next season, intend to change their names to the Toronto Jays. It just sounds friendlier, I guess, sort of like the Bullets becoming the Wizards--screw nearly 50 years of history.
The last such nickname change without a relocation was the Houston Colt .45s-cum-Astros. Many teams have changed their names over the years, especially in the early days when the names were not yet official. In the Fifties, because of the Red Scare, the Cincinnati Reds briefly changed their names to the Red Legs (I heard, I believe, YES's Michael Kay say that he liked that the team used the old-time name when it appeared in the graphic. The Red Legs was no more an old-time name than the Red Storm of St. Johns).
Poor franchises changed their name often. The Phils changed theirs to the Blue Jays (fancy that) during World War II. The Braves were the Bees in the late '30s. The old Washington Senators were officially the Nationals, but no one called them that. The Dodgers, back when they sucked, were known as the Robins as late as 1931 for manager Wilbert Robinson. And the Yankees were originally the Highlanders (like the Jets were the Titans in the AFL and the Nets, the Americans in the ABA).
Of course, in the early days before the names were official, teams changed names like Sox. The Pirates were the Innocents (as well as the Pittsburg Alleghenys: the H had yet to be added to the city's name). The Cardinals were once the Brown Stockings. The Boston Braves were originally the Red Stockings (the team became known as the Doves when they went to all-white uniforms and were purchase by the Dovey brothers; the AL team stole the name before the original Red Stockings could change their uniforms back and with it, the city's hearts). The Cubs were the White Stockings (and Cap Anson's Colts while he managed and the Orphans when he left). The Phils were the Live Wires and the Quakers. The Dodgers were once the Bridegrooms because a number of players were married in one season.
The best and most varied names may belong to the Cleveland AL franchise: the Naps (for Nap Lajoie), the Bronchos (yes, with an H, maybe they gave it to Pittsburg), the Blues (huh?), and the Molly Maquires.