The President isn't beholden to any of these folks. The parties are thrown by national and state organizations for those who worked to support the President. In the case of the youts concert, it was given by a group that wants to encourage youth volunteerism. That is something the President supports, but it doesn't mean he's beholden to the group in any way.
In other cases, parties are hosted by state volunteer organizations. Ohio, for instance, is having a party, and has invited a young lady who lost her mother in the attacks on 9/11, and who was featured prominently in an ad for the President that is credited with helping him win in that state.
Even Free Republic is having an Inaugural Ball, and lots of Freepers plan to attend. I don't think they have any illusions that their throwing a party celebrating the President's victory makes him beholden to them in any way.
Yup. All those corporations are coughing up all those shareholder dollars just because they are caught up in the exuberance of the moment. Yup. No influence peddlin' here...
But the Democrats do it too, so we shouldn't complain.