Another great resource, if you are looking for a particular musical talent, is kompoz.com
It’s how my band collaborate. Basically, you upload a track (could be music, lyrics, vocals etc) and advertise what help you need. So for example, you may need a bass player or an engineer and if people like it, they’ll join you.
Membership on Kompoz is free but has paid levels of membership (if you want to use better quality than mp3 tracks, or if you want to create more than so many songs.
It’s worth a look, if you’re stuck for that bagpipe player that will take your song to the next level