Migration question.

[Southernboyj]

I currently own an iMac and a rMBP. I am wanting to sell the iMac however.
I do not currently own an external hard drive however I do plan to buy one in the near future. In the mean time I'd like to move everything over from my iMac's hard drive to my MBP's SSD. My question is, what is the best way to get my iTunes library/backups fully moved over so they can be sync'd with my mobile devices?

 

[PerformaGuy]

You can use Migration assistant over Wi-Fi (warning: can be slow).

See here:
http://support.apple.com/kb/HT4889

For iTunes sync, consider looking at SuperSync:
http://www.tuaw.com/2012/10/02/supersync-5-will-add-support-for-itunes-match/

 

[Dark Void]

How much data do you need to move over? If it's just an iTunes library then move your folder onto an appropriate sized drive (Flash/HDD) and transfer it over that way.

I am not sure that there is a way to "add" your hard drive to another, only replace. You have to manually transfer files over.