Satish Dharmaraj, the co-founder and chief executive of Yahoo-owned communication company Zimbra, has made a personal investment in web meeting startup Dimdim.

Dharmaraj says he put his money into Dimdim because its technology complements Zimbra’s. Both offer open source software for different aspects of collaboration. Zimbra — which Dharmaraj sold to Yahoo for $350 million last year, and which he continues to lead from within Yahoo — offers a desktop client that incorporates email, documents, task management and more. Dimdim provides a basic suite of web meeting features which you can use for free (making it a more affordable alternative to web meetings products like WebEx and GoToMeeting).

It looks like there’s more news about Dimdim/Zimbra collaboration coming soon; in the long-term, a single product that incorporates Zimbra and Dimdim’s tools would be pretty cool.

The size of Dharmaraj’s investment was not disclosed, but he is taking a seat on Boston-based Dimdim’s board. Dimdim announced $6 million in venture funding back in June.