I know this is planned, but though I should add a formal feature request.
It would be great to be able to import relationship data for your supporters via .csv.
This is more of a bug/issue than suggestion but here's the problem. If you are asking your supporters to give monthly or buy memberships that recur monthly through a membership sales page they are then directed to donation page. If you have that donation page powered by Paypal Payflow Pro (or possibly any payments processor that doesn't support monthly giving) people are still able to complete the transaction without an error message (internal or external).
The effect of this is that an organization can be thinking that they're collecting and growing their monthly donors/members but are actually only capturing one-time donations.
It would be great if we could include the option to allow petition signors to select from a tag list when they're signing a petition.