Twitter is the hottest thing on the net right now, but it can easily get overwhelming when you follow a large number of users. Many people, including myself, have utilized Yahoo’s powerful Pipes mashup tool to make feeds and interfaces to help wade through all of the data.
Never heard of Yahoo Pipes? It is a composition tool to aggregate, manipulate, and mashup content from around the web. It has a very easy to understand (and memory intensive) user interface, that illustrates the dataflow from module to module.
Basically, if the data you want can be obtained via RSS, XML, ATOM, etc, you can integrate it into your mashups. But chances are someone has already built a pipe to do anything you need, as there are thousands of pipes using data from all over the web. Yahoo allows any piped to be “cloned” as your own, so find something similar to what you need, clone it then tweak it how you see fit.
As far as Twitter goes, here are some of the more interesting ones that have been cloned often.
Tweets Nearby – See the tweets happening near a Twitter user's location.
Friends Name Alphabetical – Helps overcome a simple flaw on twitter, when you have a large number of followers.
Twitter Friend's Favorites – Easy way to see the “favorite tweets” of people you follow.
Local Twitterstars – This pipe returns the most-followed Twitter users from a geographic region.
True Twitter Friends – Shows all twitter’s who you’ve had a conversation with.
Twitter Monitor – A twitter observer. Simply enter a keyword you want to monitor and it will mashup data from terraminds, tweetscan, twemes and summize.
Social Media Firehose – This is a social media search for tracking brand or product mentions on a slew of social media sites, including flickr, twitter, friendfeed, digg etc. It taps into their search APIs directly, so it's much more immediate and comprehensive than say, Google alerts.