These are not originally designed for Blackberry but works great with the Blackberry in my experience.
www.IMBOT.com/mobile - Text to voice (send emails to a phone number!)
www.phonewire.com/voicemail - Voicemail box with automatic voice-to-text email transcriptions
www.dictomail.com - Voicemail box with auto voice-to-text email transcriptions
www.efax.com - An Internet fax that works well with Blackberry (see other thread)
etc.
Feel free to ask questions, and if you know of any other services that enhance the Blackberry. For now I have posted this thread in "3rd Party Software", but I have also contacted Guess about which forum this post is most approprate for (or rename this to "3rd Party Software & Services")