Okay this list is not definitive and anyone not here should add a link to their party/gathering in the comments. SES NY is one of the major events of the search year, so I hope many of you are attending. If not there will be people from all over live blogging the sessions.
So this is what I have so far;
Monday night Meet and Greet at the Hilton starts at 6PM
Tuesday there is a ScmoozeFest and Happy Hour for Affiliates - a group of sponsors and it is at Dave and Buster's so is always fun. So stop by and have a couple of drinks and some appetizers. Runs 5-7:30pm
There is also a SEMPO gathering at the Hilton - come meet the new board and have a drink. Starts at 7pm and location is on the Meetup site listed above.
There is an unconferenced Black Hat White Hat sessions at the Bridges bar in the Hilton - space is limited so this should be fun.
Charity Party being run by WeBuildPages This is at Hurley's on 48th from 8-10pm and costs $30 for open bar - great deal - and money goes to the Homeless.
I will update as I hear of other things too.