Gay-Popular Events and Festivals:

Mid-March: Taste of the South End (a food festival benefitting AIDS Action Committee of Mass.).
Mid-March: St. Patrick's Day Parade (it's a huge in Boston, but it also bans GLBT groups from marching, making it one of the city's most controversial and least-inclusive festivals).
Mid-April: Boston Marathon.
Early to mid-June: Boston Pride festival and parade.
Early July: 4th of July Boston Pops Concert and Fireworks.
Early July: Boston Harborfest.
Late October: Head of the Charles Regatta (a major intercollegiate rowing event that draws thousands of athletes and spectactors).
 

Resources on Gay Boston:

A number of resources out there offer extensive information on the city's gay scene, including EDGE Boston, Columbia Fun Maps Boston guide), the popular biweekly newspapers New England Blade and Bay Windows). The Boston Globe-owned Boston.com) is the city's best mainstream news source.

Downtown Boston Highlights:

The leafy Boston Common (and adjacent Boston Public Garden) has been downtown's hub since 1630 and remains a joy to explore. Just north is the largely colonial Beacon Hill neighborhood, with its brick sidewalks, townhouses, and fancy boutiques. Northeast of the Common you'll find the touristy but fun Quincy Market, loaded with shops and restaurants. Walk the nearby Freedom Trail for a 1.5-mile tour of New England history, or head east to the fantastic New England Aquarium. Nearby is Boston's North End, a network of narrow, crooked streets and 19th-century brick tenements that house a prominent Italian community.

Exploring Gay Boston Neighborhoods of Note:

The South End: Boston's most gay-identified neighborhood has also become one of the city's most pricey and exclusive. Most of the neighborhood's bowfront redbrick homes, many embellished with elaborate details, were built in the 1850s. The area devolved into blight steadily throughout the 20th century, before experiencing major (and gay-inspired) gentrification in the early '80s. Its primary commercial spines, Columbus Avenue and Tremont Street, are loaded with gay-popular restaurants, cafes, and businesses. Farther south, Shawmut Avenue and Washington Street have become the city's latest hot spots, with scene-y restaurants, loft condos, and such.

Back Bay and the Fens: The relatively young Back Bay - with its broad avenues of four-story townhouses, sidewalk cafes, and swank boutiques - recalls Paris; it's still one of Boston's preeminent residential districts. The 62-floor John Hancock Tower and 52-story Prudential Center, the latter surrounded by a massive indoor shopping mall called Copley Place, dominate the skyline. West of Mass Ave is the Fens, the final piece in Boston's jigsaw puzzle of landfill, an amalgam of residential and industrial blocks and site of Northeastern and Boston universities (plus Fenway Park). Plenty of gay folks live in both neighborhoods. Back Bay Fens Park, designed by Frederick Law Olmsted, contains the esteemed, newly redesigned Museum of Fine Arts and fascinating Isabella Stewart Gardner Museum, a stunning, idiosyncratic collection of art and furniture.

Jamaica Plain: For many GLBT folks (especially lesbians), Jamaica Plain is Boston's top "streetcar suburb," known for placid Jamaica Pond and the once-exclusive residential neighborhood around it. This enclave has been rediscovered by city dwellers in search of relatively affordable housing. Check out the handful of homo-popular restaurants and businesses along Centre Street.

Cambridge: Often lumped in as just another of Boston's many neighborhoods, Cambridge is actually an independent city of 100,000. It was settled in 1630 and six years later became home to the nation's first university, Harvard, which todays anchors Cambridge and is surrounded by superb museums plus dozens of great restaurants and shops. To the southeast, the Massachusetts Institute of Technology fringes the Charles River near Kendall Square, a small dining and shopping hub. Cambridge, along with Watertown to the west and Somerville to the east, has many gay residents.

Compliments: About.com Gay & Lesbian Travel