TwitHive is a new Twitter web client with many great features, including channels and multiple accounts.
List of all of the features:
100% web browser based application.
Monitor Tweets across multiple accounts by adding more than one Twitter account.
Track trends and brands mentions with customized keyword search channels.
Easily interact with your Twitter contacts with one click retweets, automatic url shortener, and more.
Keep your Twitter passwords secure and safe by using OAuth based authentication.