Good for new contributors:

• http://yourfirstpr.github.io/
• http://openhatch.org/
• Find new-contributor-friendly organizations on https://summerofcode.withgoogle.com/organizations/

Multi-project issue aggregators:

• http://24pullrequests.com/
• https://www.codemontage.com/
• http://www.codetriage.com/
• http://www.lookingforpullrequests.com/
• https://bountify.co/
• https://www.bountysource.com/
• http://issuehub.io/
• http://up-for-grabs.net/

Listings that include non-technical opportunities:

• http://whatcanidoformozilla.org/
• http://socialcoder.org/

Servo issues:

• http://servo.github.io/servo-starters/

Rust issues:

• https://github.com/issues?utf8=%E2%9C%93&q=is%3Aopen+is%3Aissue+language%3Arust
• https://public.etherpad-mozilla.org/p/rust-curated
• http://edunham.github.io/rust-starters/