At its core, Momento (made by the UK-based d3i) is a straightforward diary app. It allows you to easy write “Moments” (diary entries) to express what you are doing or feeling on any given day. It takes the process a step further by allowing you to tag friends (from you iPhone contact list), places, events, and add photos to these entries. But the real killer feature of the app is that it also allows you to import bits of information from a number of services including Twitter, Foursquare, Gowalla, Facebook, Flickr, YouTube, Vimeo, Digg, and any RSS feed. The result is a brilliant log of almost everything you’re doing online.
The key to Momento is that all of this information is for you and you alone. You import social items, but it never sends anything out. It’s simply a way for you to log and keep what you did on any of these services in a given day. And it’s all presented in a very nice, easily accessible package.
I've been using Momento for about a month now and I love it. Since Momento v2 came out with its added feeds for foursquare and RSS feeds I've got a lot more from it, allowing me to use my foursquare check-ins to frame the rest of my content, and reducing even more the added context I feel I need to give to my moments (and as a side benefit making me use foursquare more often).
My Mum was a regular diary writer, usually documenting facts rather than feelings. Except for short periods during my teenage years, I've never really kept a diary, instead relying on blogging as my method of recording facts - mainly as it comes with a search function - but over recent years it hasn't just been blog posts, it has also been tweets, uploads to flickr etc. Because my days are almost always filled with some element of social interaction or other - twitter, flickr (especially with my 365 photo project going on), there aren't gaping holes in my calendar, there just may be some without red blobs (which indicate moments rather than feeds) and that reduces any pressure I would feel if I were diarising "properly".
In short, an app that scratches an itch, and scratches it well.