Given the popularity of Tumblr as a CMS and blogging platform, and understanding that dlvr.it users definitely require the flexibility to direct content where (and when) they need it, this is a no-brainer feature.  What's more, with the APIs already playing nice with each other, enabling sub-blogs for Tumblr users would not require much overhead, yet would expand dlvr.its userbase while offering existing users even MORE wonderful options for curating their content.

Please think about it?

This needs to happen.  Pronto!  :-/

The only known work-around - namely, creating a second, third, etc. Tumblr account (each with different login credentials) - is absurdly complicated and annoying to your userbase.

Your fine service is totally useless to me then.   Bummer.  It's next to impossible to use totally separate Tumblr accounts.