
iGetcha.org is a suggested opensource and free software directory for the technological sustainability of nonprofits. It's also a simple, non-techie shortlist to assist organizations with a SOHO.
Recently, Gizmo5 was taken over by Google so keep on the lookout for the Google Gizmo5/Voice application to compete with Skype. And it seems it may be here with free calls on Gmail.
If you'd rather choose something other than Skype, the iGetcha team has heard positive remarks about Gizmo5. This can be an alternative to Skype but again, our sources prefer Skype's quality. Gizmo5 can also be an alternative if you want a separate VoIP from Yahoo!, Gtalk and Skype since most users and friends may be on these mainstream applications. In this way, you can keep work isolated from personal chats :) Of course, you can always create multiple accounts on your favorite Internet Telephony application.
If your nonprofit is in the US, you might want to try Google Voice. As described in our post, this software is only by invite at the moment, but it is free technology alternative that gives you a free local number. The iGetcha team encourages you to keep checking for Google Voice to be released to the public.