Both penguin and T11 marketplace are where I have everything published. These are the ways to go if you want to self publish. If you want sponsorship, then you will need to convince the company you are pitching to that your product is worth their time. I have over 20 effects published currently and all of them are published either on the marketplace or Penguin.
I agree with chris that penguin has a bigger following and you will sell more there. I like T11 because the community here is a lot better IMO.
Companies I would try to pitch to if you want sponsorship: Ellusionist, Theory 11, Penguin, Lost Art, Shin Lim, Murphy's Magic, and Vanishing Inc.
If you are not sure what I mean or the difference between self published and sponsored, here is the deal:
-Self Published: You will have to film everything yourself and upload it to either the T11 Marketplace or Penguin Partner Program. You will need to do all of the marketing and advertising yourself, HOWEVER you will make more in royalties this way.
-Sponsored: You will pitch your product to the company you want sponsorship to. They will film everything and do all of the marketing and advertising for you, however they will usually ask for exclusive rights to your effect and you will not make as much money off of it in royalties. Usually they have to really want your effect for it to get picked up, but if it is groundbreaking, this will be a good way to get your name out there!