I have been using Org-mode with Remember the Milk quite nicely. here is my setup:
(require org-feed)
(setq org-feed-alist
'(("Remember The Milk"
"https://www.rememberthemilk.com/rss/jonnay/"
"~/org/GTD.org"
"Remember The Milk"
:template "* TODO %title\n %a\n "
)))
;;* rtm feed timer
(run-at-time 3600 3600 'org-feed-update-all)
The only problem is that I get asked for authentication the first time I start up emacs. With a bit of elisp this could be fixed, I just haven’t had time yet.
Just as an update, there is a new package shaping up that might handle syncing a little better: http://orgmode.org/worg/org-contrib/gsoc2012/student-projects/org-sync/index.html