I logged into my account this morning and saw that I've personally invited 100 people into Sendside.
By the way, we've left our Beta and released v1.0 for our Personal and soon to be released Business and Enterprise Editions. If you'd like an account, fire me off a request through the link below and I'll set you up.
Of interest may be that <jeffbarson> following my name. It's my Sendside 'Member Name' and with this new release you can now send directly to that and I'll receive that message. In future releases you'll be able to send to other unique identifiers just by typing them into the TO field. If they're unique, they'll be delivered directly to that recipient's Sendside inbox.
The takeaway here for all of you 'social network types' is that Sendside doesn't rely on your email address but identifies you in the same way that you're identified by all of your unique identifiers offline.. as an individual with a unique identity. Cell phone, email address, social security number, street address, military ID, name... anything unique, or any unique combination of identifiers could be used to send a message.
There are plenty of identifiers you can send to, but they're generally some sort of username inside the network. As far as I know, Sendside's the only network that has the potential to combine ANY online identifier as well as all things offline to determine exactly who you are and deliver content to you with total precision and security.
That, buy the way, is tres impressive.