Shameless plug: you might like Remembary (http://remembary.com/) - it's based more around writing in your diary, but it also pulls in Twitter and Facebook and RSS feeds like Momento. It also automatically finds the pictures you took each day, and puts any geotagged stuff into a no-work-required map. It automatically fetches your calendar entries (well actually it doesn't at this exact moment due to an iOS6 bug but it will in about a week), It doesn't have a desktop client but it was originally built for iPad and now has an iPhone version. It has a manual data export/import option instead of 'syncing' but I decided that privacy is more important than seamlessness. It doesn't really have tags or address book integration, but given your other other requirements I think you might find it interesting.