Type in your tumblr.com username and you'd get the tracks that are played on that tumblr blog of yours. Isn't that amazing. Yes, it is because no other blogging service does that. Tumblr.com is simple, unique, and above all user friendly. It's reblog service is all Cool with a big 'C'. Reblog is tumblr reposting option. You just go to any post you like on any tumblr blog and there comes an option on the top right corner (obviously, you need to be signed in to do that) and you just click on 'reblog' and it'll take you to the your blog's tumblr editor. And there you can reblog.
A 52 sec. video will explain the reblogging option in tumblr.