http://packages.synocommunity.com
http://e-remonty.info/spkrepo/packages
http://packages.missilehugger.com/
http://www.cphub.net/
http://synopkg.superzebulon.org/spkrepo/packages
http://packages.pcloadletter.co.uk/
http://update.10trum.de/packageupdate/getpackages.php
http://synology.mdevries.org/spkrepo/packages
http://synology.sysco.ch
http://packages.hoel.dk/
http://spk.q14six.de/
http://packages.quadrat4.de

Synology Package Sources Monitor (not source)

http://dottoremoe.com/synomon/