Hipster start-ups unite; New York-based Tumblr and Berlin-based Soundcloud announced a beautiful partnership yesterday. “Tumblr <3s Soundcloud,” Tumblr declared in a staff blog post, while the music start-up announced the news in a post entitled “Tumblr + Soundcloud = <3.” The partnership means Tumblr users can search Soundcloud tracks from within Tumblr and post an unlimited number of them a day, and Soundcloud has embedded Tumblr share buttons all over its site and mobile apps. Soundcloud, which lets you upload files of any size, is mostly remixes and original tracks by independent and amateur artists, although it does have a sizable library of better-known songs.