I would like to suggest a matchmaking event during alumniunite. Basically, people are matched based on interests, which can be anything. Doesnt have to be startup oriented, anything people are interested in and would like to find people to geek out with. For example energy policy, smart grids, big data, AI, electric mobility etc. etc. This would also enable networking beyond our friend circles.
Groups can later be formed and continued over the community platform. Based on number of groups formed and the activity in the group, the outcome of the event can be measured (this quanitfication of the results of event is seriously missing!!).
Something like this could be used: Event Management Tool for Matchmaking and Brokerage Events | b2match