I think you want two services here; Instapaper for the offline reading part, Pinboard for the archive part. I use Instapaper for the 'read later/offline' stuff,

I think you want two services here; Instapaper for the offline reading part, Pinboard for the archive part. I use Instapaper for the 'read later/offline' stuff, as a) it works on the web, iPad, iPhone, & Kindle and b) it's great at syncing. Pinboard will let you save URLs and tag them, and with a pro account it'll keep a copy of the page for you.