DTM magazine is offering free downloads of the Miku Append demo for the "dark" and "soft" voices. Just need to fill in a short survey.

http://www.dtmm.co.jp/archives/append/miku_enq.html

In case you're wondering what the questions are:

1. Which Vocaloids do you own?
2. Have you ever uploaded your songs made with Vocaloid online? A: yes; no
3. How many years experience do you have with DTM (making music with a computer)? A: just started; less than x years; between 1 - 2 years; etc...; over 5 years
4. Which DAW program do you use mainly? A (the japanese ones): freeware; don't have any
5. Please write any opinions, requests, etc. you have about Vocaloid.

Note: Demo is limited to 14 days after installation. Also, VSQ cannot be saved, though you can export your work in WAV.