Avis
Avis "Message Center" is an exclusive international round-the-clock leave and retrieve message center offered in 25 countries worldwide - 18 in Europe - via special toll-free numbers for each country. The service is available exclusively to Avis renters on the road at no extra charge 24 hours a day, 7 days a week.
http://www.avis.com/AvisWeb/JSP/US/en/programs/consumer/ intl_assistance_message_cent.jsp

Callwave
Read your voicemail messages on your mobile or computer, or turn your computer into an Internet answering machine.
http://www.callwave.com/

Digitalmail
Voice forwarding to email service using a unified messaging mailbox, which means you can listen to your calls from anywhere in the world.
http://www.digitalmail.com/

Drop.io
Leave a message, record a speech or lecture, keep a personal audio journal, or create a podcast, which can then be listened to, downloaded or shared with whom you choose.
http://www.drop.io/

Evoca
Create voice recordings using your telephone, PC microphone or Skype, save them on the Web, and then organize, email, share or search through them.
http://www.evoca.com/

Grand Central
Provides you with a unique number that lets you pick up calls and voicemails from any of your exisitng phones.
http://www.grandcentral.com/

Hotvoice.com
Send voicemail/fax messages anywhere by simply making a local call from any telephone or fax machine to any of the company's gateways in different countries.
http://www.hotvoice.com/

Onebox.com
Pick up voicemail messages at your Onebox phone number. You can also use it to receive faxes and emails.
http://www.onebox.com/

Pinger
Send voicemail messages to multiple mobile phones with just one call.
http://www.pinger.com/

SpinVox
Convert your voicemails into text messages and send them direct to your cell phone or email box.
http://www.spinvox.com/

YackPack
Lets you record online voice messages using a web browser and a microphone, which can then be shared privately or publicly, stored online, or embedded in a website.
http://www.yackpack.com/