A sort of next generation voicemail services, based out of Aliso Viejo.  They went live with their public beta last month, and earlier this month announced that they received their first major round of VC funding (totaling 4.5 million from VantagePoint Venture Partners).

Youmail is all about customizing your voicemail experience.  You can give each caller a customized voicemail message, so if you want to leave your family and friends various fun messages while leaving a more serious message for work colleagues and unknown callers, you can.   Basically its very similar to customized ringtones for callers.  Another interesting feature is the ability to "Ditch" a call, by answering with a voice message but immediately hanging up after the message is played (fun for pranks or maybe that annoying stalker of yours).  Finally, Youmail also allows you to access your voicemail over the web, which could come in handy if your cell phone is dead or if you want to share a funny message you received with your friends.

In our tests with YouMail we were impressed with how easy and well it worked.  Really the big issues facing Youmail are less about technical merit and more about business and marketing.  Will the added functionality in YouMail be enough to convince people to use it?  I'm not necessarily sure, as I personally don't have enough interest in customizing messages for people.  I'm busy enough as it is, and I have little time or interest in making custom ringtones for people, let alone custom messages.   Of course I'm sure that I'm not the primary market demographic; I suspect Youmails biggest uptake will be highschool kids who incessantly use their phones (the ones who somehow send a 1000 text messages a month).  Ultimately YouMail success will hinge on whether it can convince enough people to use their service, and manage to make it without the carriers adding these features on their own.