There are lots of royalty free music sites out there to submit your music to but there are more and more sites appearing that actually pitch your music to certain projects and producers for free or for a fee. There are also a few crowd-sourcing / collaboration type sites here.
These sites are distinctly different from the free-for-all type sites like productiontrax, audiojungle and audiosparx and might be an interesting addition to your search for outlets for your production music.

1. Humtoo.com
http://www.humtoo.com/

A global meeting place for music makers and content creators. This site is pretty cool as it is free to signup and submit your music to videos and project descriptions.

2. Film Music.net
http://www.filmmusic.net/
Paid monthly subscription to submit music to be considered

  Immediate Access to our Film/TV Music Jobs Database
Access to Film Music Network Live! 24 hr/day streaming audio of Film Music Network events
Immediate Access to our Film & TV Music Salary & Rate Survey
Full benefits and discounts at all participating Film Music Network Vendor Partners.

3. The Composer Collective
http://www.thecomposercollective.com/tcc/composersignup.asp

The Composer Collective is comprised of cinematic composers dedicated to creating dramatic scores of the highest quality for film, television, interactive and commercial media. We group composers into innovative and productive workforces, giving the film industry a much-needed resource for intelligent music at never-before-seen productivity levels. This service is known as TeamScore™.

Choosing TeamScore™ puts you on the front lines of the film business as it changes and adapts rapidly to the demands of distributors and consumers worldwide.

4. Taxi.net
https://www.taxi.com/join/?88.7.207.46.6651122970743537
Paid yearly subscription is $299.95

http://www.taxi.com/abouts/join-whatyoullget.html
More than 1,200 opportunities per year to pitch your music to Major and Indie Record Labels, Top Music Publishers, and Music Supervisors working on film and TV projects. That’s TEN TIMES the number of opportunities you’ll get with TAXI imitators! And don’t forget, we have opportunities in nearly every conceivable genre of music.

5. Broadjam
http://www.broadjam.com/delivery/index.php?sessionID=q4qqrqkt2vc05bi4s15palahj1
offers an ‘opportunities’ service for $5-$10 per sbmission depending on what type a paid account you have

a broadjam member to enter opportunities. sign up today. you’ll also get other services designed to help independent musicians like you, promote themselves.

6. Studentfilms.com Forum
http://forums.studentfilms.com/eve/forums/a/frm/f/6156029451

Jobs posted for composers and composer submitting their resumes and profiles. Free to register.
Lots of posts like ‘Composer Needed’ and ‘Composer Available’.

7. Soundreef (beta)
http://www.soundreef.com/private_beta/promoterPage?o=13

Swap music for promotion? Not sure what that means but worth investigating.

8. YouLicense
direct job opportunities are available here
http://www.youlicense.com/Opportunities/default.aspx

here’s the RSS feed for the jobs list 
http://www.youlicense.com/XML/RSS/Opportunities/YouLicenseOpportunities.xml

9. Minimum Noise
http://www.minimumnoise.com/
A new site with all kinds of projects for "crowdsourcing musicians".

10. Pump Audio
http://pumpaudio.com/artists/index.php

There is no submission fee. If your music is not used, you lose nothing.
You will receive 50% of the license fees we receive for your music.
Pump’s deal is completely non-exclusive.
Our deal will never prevent you from working with anyone else.

11. Musicdealers.com
http://musicdealers.com/
A new site where you can upload and create a profile and the people at musicdealers pitch your tracks to potential clients.

12. Musicloops.com
Our site where you can submit a demo. No fees to join. Price your own tracks, lots of sales, with 50% of the price goes to the composer.