Calls over wifi?

My girlfriend is headed overseas next week. We're trying to figure out how to use our phones to make calls over wifi. She has an Incredible and I have an Eris (both on Verizon).

It looks like we can't use Skype because it requires Verizon network coverage to work. It looks like Gizmo5 with Google Voice may have been an option at one time, but Google shut that down by acquiring Gizmo5.

So my question is, is there any way that we can make calls to each other over wifi?

 

Has anyone tried fring? Do you have to pay anything if you are making a skype-to-skype call over wifi?

 

We checked out the Vonage app last night, but we were both a little worried about the privacy issues. It looks like Vonage has a lot of access to your facebook account and could take your data if they want.
I'll give Nimbuzz a shot when I can get home and set it up tonight.

 

I gave Nimbuzz a try last night. It looks like it will work for calls over wifi, which is awesome. On our test run last night, we could hear each other, but both of us would get a 2-3 second delayed echo. Anyone else experienced this or know a fix?