Tradeshows:

Jan-Feb 2013
Spielwarenmesse, Jan 30-Feb4 Nürnberg, Germany
A trade only show which is the largest in the world, I believe. A fantastic intro to all the game and toy manufacturers in Europe.
NY Toy Fair, February 10-13, New York, NY
The preeminent US trade-only show for the specialty and mass markets. If a company sells to these markets, they will be at this show.

March 2013
Toy Fest West , March 10-13, Las Vegas, NV
For game buyers that do not come out to NY for Toy Fair, this is another option for them on the West Coast, run by WTHRA. A much smaller, more intimate fair. Often sales reps are manning the booth rather than the actual game companies.
GAMA, April 18-22, Bally's, Las Vegas, Nevada
One of the first-of-the-year trade shows for the hobby market. An excellent place to catch up with the folks in this industry to find what the new releases will be for the year.

April 2013
none

May 2013
UK Games Expo, May 24-26, Birmingham, UK,
The UK's biggest gaming convention with plenty of drop-in and organized play sessions and two days of demos, tournaments, role-playing, and game company exhibits.

June 2013
Toy & Game Expo, June 8-10, Sydney, Australia
Australia's premier public toy and game event for the exhibition and demonstration of all the latest games and toys.
Licensing International Expo, June 18-20, Mandalay Bay Resort, Las Vegas, Nevada
The world's largest brand and property trade show. Find out what movies are coming out, which books need games, and which licenses will be hot.
ASTRA Marketplace & Academy, June 16-19, Nashville, TN
American Specialty Toy Retailers Association's industry show targeted specifically at specialty retailers in the U.S.
Origins, June 22-26, Columbus, Ohio
Another great hobby industry trade event. Also tied to the Academy of Adventure Gaming Arts and Design awards (often just referred to as the Origins awards). \
American Library Association Exhibit, Jun. 22-28, New Orleans, Louisiana
As libraries across the nation start making games a core part of their community-centric initiative, this show is fast becoming a key show for game manufacturers.

July 2013
Protospiel, to be announced, Ann Arbor, Michigan
Started in 2001 by game designers Stephen Glenn, Dominic Crapuchettes, and Mike Petty, Protospiel is an annual get-together of amateur and established game designers to test and promote nearly-finished game prototypes. The atmosphere is casual, yet everyone is serious about their goals and dreams of publishing games. There are now a few other Protospiels in other parts of the U.S. which can be found thru this site.
Comic-con, July 18-21, San Diego, California
Everything comics. Tons of artists, graphic novels, anime, tv and movie release features and more.

August 2013
GenCon, Aug 15-18, Indianapolis, Indiana
The biggest open gaming convention in the U.S. All the major hobby game manufacturers show their releases for the year. Tons of gaming areas and special events.

September 2013
none

October 2013
Fall Toy Preview, Oct 1-3, Dallas, Texas
An appointment-only trade show where all the major manufacturers meet with all the major accounts for a sneak peak and what is in the works for games and toys.
International Spieletag , to be announced, Essen, Germany
The biggest (and best) open-to-the-public gaming event in the world. Draws more than 150,000 people each year. The best chance to see all the European releases before the Holidays. Also timed with the announcement of the Spiel de Jahr winners.

November 2013
BGGcon, to be announced, Dallas, Texas
The largest community of gamers, BoardGameGeek.com, hosts their annual con. A great event filled with lots of dedicated gamers.
T&G Con, Nov 21-22, Chicago, Illinois
The two days leading into ChiTAG, this Toy and Game Inventor Expo, offers practical advice on how to get started inventing, licensing and publishing your own creations. Hosted by a magnificent panel of experts.
ChiTAG, Nov 23-24, Chicago, Illinois
An open-to-the-public long gaming weekend akin to Essen. Lots of gaming areas and an ever-growing amount of exhibitors. Quite a few special events as well, including a Young Inventors contest.
i-SPI, Nov 21-24, Chicago, Illinois
Running concurrently with T&G Con and ChiTAG fair, this is a by-invitation-only professional toy and game inventor summit.

December 2011
none

January 2014
Hong Kong Toy & Game Fair, Jan 6-9, Hong Kong.
A trade only show which has been growing in significance in the last several years.
UK Toy Fair, to be announced, London, England
A trade only show is expressly for UK manufacturers of toys, games and hobbies to exhibit their upcoming products for the year.

March 2014
NSSEA EdExpo, March 8-11, Dallas, Texas
This trade show is a back-to-school extravaganza. I have heard that a good number of game companies have been well-received here.

And of course there are countless others depending where you are in the U.S. or the world. Info on these you might find through Wikipedia list of cons found here. Or at Game Convention Central, found here.