I would like to say Ekiga for me since, it was ekiga on ubuntu that got me aware of SIP/VOIP and I have not looked back ever since.

Ekiga for me too :-)

We still vote for XMMS, don't we?

Jeremy, IHU works well and the beauty about its complete decentralized nature and fashion is that no one can know how many people really are using it.

For the next time, please add IHU and other VoIP applications like Gajim, Pidgin and Psi.
BTW, by seeing Pidgin on the list, more users will be aware of its VoIP capabilities with Jingle of XMPP.
There is nothing wrong by posting the same application in both IM and VoIP lists at the same time, with exception for Audio/Video which should be separated.

Tryum
I don't think it is good idea. If it has VoIP capabilities and user use it, some user will want vote it here(and so ask to add it into poll). Polls aimed to get people favourites, not to influence it. If nobody voted Pidgin as VoIP, it means it is not worth it. Adding to poll nobody known, and nobody used piece of software is looks like advertisement an so influences true picture. By the way, Asterisk is also very good "VoIP application", and I'm sure there are a number users here in LQ which use it, but it doesn't means it should be included here unconditionally

Don't forget to vote for Shoretel from Shoreline Communications as the most robust industrial grade Voip out there.