Vonage, huh? Most interesting...as not just a Vonage customer, but someone who constantly touts the benefits of Vonage (I've got 4 referrals so far) I'd be most interested to see what they come out with. Ok, while I'm on my pro-Vonage rant, last night was a classic example of why anyone with broadband should be on Vonage. We had a power outage, which in the normal world would make you VOIP phone useless, right? Well, Vonage to the rescue! I had set my account up so that in the case where the VIOP converter was unreachable, for whatever reason, all calls would be transfered (free of charge, of course) to my cell phone. Well, I had completely forgotten about that until my cell phone rang a few times more than usual last night and the lighbulb went on over my head...Vonage is doing what it's supposed to do...seemlessly and flawlessly.
But, I digress...yeah, a voicemail app would be cool! 
Ghostlobster
Very happy convert to SageTV! Finally, watching ESPN-HD in real HD on my HTPC without having to deal with the CableCARD fiasco!