There is a lot of information passing through FriendFeed. The web interface is useful up to a point, but sometimes people feel they are missing interesting items, or they just do not like the interface. There are a lot of applications trying to make things easier as well as a wealth of Greasemonkey scripts. This list is meant only to be a list and not an endorsement of any of these applications.
bTittleTattle by Sobees is a Windows-only desktop application with support for both FriendFeed and Twitter. It looks very different than any other application listed, as it conforms to the Sobees customizability of all their applications.
MySocial 24×7 is a Firefox plugin that loads as a sidebar. If you live in your browser, this is a decent option. Even though it is a FriendFeed client, it does support replies to tweets being posted back to Twitter.
FriendFeedMachine is a web client that presents your timeline with information popping out in separate modal windows. The main differentiator here is the ability to tag friends as “good friends” so that their activity is grouped in a separate list.
NoiseRiver is a web client that targets your interests in order to give a unique presentation of the timeline items. You adjust keyword interestingness and friend interestingness, and the items are displayed with green or red highlights depending on the similarity to your interests.
mioNews is another web client that displays your friends activity in an interface similar to most email clients. You can group users in folders and create a topic by entering a search keyword. This is for people who do not want to miss anything and are extremely organized.
Feedalizr is a desktop Adobe AIR client that supports posting to FriendFeed, Twitter, Flickr and Jaiku.
FF To Go is a mobile phone client that was created prior to the iPhone interface developed by FriendFeed. Many mobile FriendFeeders still feel that FFToGo is the better application.
ffapps.com has an interesting list of stuff, mostly Greasemonkey scripts at this time.
Moopz is yet another web client with a twist. There is a sidebar with the popular posts, a tag cloud as well as a list of quiet posts.
FriendFeedMachine, NoiseRiver and mioNews were reviewed on Mashable by me. They were focused on due to the different features they offered on top of the standard FriendFeed activities.
Corvida at SheGeeks has a review of bTittleTattle focused solely on the FriendFeed integration. There is little mention of the other parts of the Sobees suite.
Sarah Perez has a review of Moopz on ReadWriteWeb. She includes an interesting idea of Moopz almost being a “fair version of TechMeme”.
This is only a list of the applications that I have found up to this point. As I find reviews of any, I will include them here as well. If you know of any additional tools or reviews, please send them my way and I will update this post. I hope this gives you an idea of what applications are there to help with your FriendFeed addiction.