Free VSTI - Alter/Ego

Developer: Plogue

From the developers website:
“Alter/Ego is based on the award winning technology featured in chipspeech but instead of targeting Vintage voice technology, it focuses on more ‘modern’ (1990+) singing synthesis algorithms and research.It is specially tailored for musical needs – simply type in your lyrics, and then play on your MIDI keyboard. It’s a true synthesizer, the sound can be extensively modified for easy and expressive performances.
And more importantly it is FREE!
Voice banks come in various styles and licenses. Daisy is the first bank available and is also FREE.
More voice banks are expected. Please visit our Voice Banks page and follow us on twitter/Facebook for up to the second news.
“

Get it here:
http://www.plogue.com/downloads#Alter/Ego

Free VSTI - Aquestone (Japanese vocal synth)

Developer: Aquest

Aquestone is a great sounding Japanese, monophonic vocal synth. It creates a singing voice from basic midi information!

[From the developers site

Aquestone is the Software synthesizer, which was developed to make people enjoy by playing real time singing performances. This software can cope with VSTi plug-in and, has the capability to output singing voice tone from MIDI information and text lyrics. We regard "real time" as the most important issue and this software runs with playing MIDI Keyboard in order to enjoy Live Performance. Of course, you can feed the data in advance.

- Singing Voice synthesis from basic MIDI information.
AquesTone does not need special MIDI information. You can enjoy the singing voice with text lyrics ONLY.
- VSTi plug-in
VSTi plug-in You can use various DAW software, which you are used to.
Also, you can connect optional effect, such as echo or reverb.
- Dynamic position change of the lyrics
You can change the position of the lyrics by forwarding and rewinding during the performance.
- Note Off lyrics
Can assign lyrics to the Note-OFF event (release event) for more intuitive play.]

Get it here:
http://www.a-quest.com/products/aquestone_en.html