Obviously there's a page on the twitter site devoted to apps but I though that a page with the most useful Twitter apps and links would be handy - primarily for me, although I'm a big fan of Tweetdeck personally. There are now so many that an exhaustive list would be a full time job in itself - so this really represents the tip of the tip of the iceberg. Please feel free to comment, add and edit...

Multi Account:

Splitweet

Reading/Consumption Tools:

Tweetdeck

Twhirl

Twickie (Thread Archiving)

Mobile:

Twitterberry

Tweetie (for iPhone)

Dabr 

m.twitter.com

Slandr

Twitstat

Tweete

Information/Brand Tracking Tools:

Tweetbeep

Twilert

Mr Tweet

Follower management:

Tweepular - The Ultimate Follower Management Tool. Find out whos following you and whos not and quickly cleanse your Twitter account of users that have not updated or are not valuable to you.

Multi-site Aggregator/Feed:

Ping.fm

Twitblogs

Lists:

UK Journalists Using Twitter

UK PRs Using Twitter

Hints & Tips:

10 Ways To Get More Twitter Followers (Kevin Rose)

How To Get More Followers On Twitter (Ryan Carson)

10 Corporate Accunts To Follow &  another article

Current 'Happenings':

TwitterTitters (Collections of short stories for Red Nose Day by Linda Jones)

Twitchhiker (Travelling on no money for 30 days, using only Twitter)

And, whilst not necessarily that useful, these are quite amusing:

How To Use Twitter For Marketing & PR

Real Time Feed Of Swearing On Twitter

Thanks

Pete Goold - Managing Director of Digital PR Agency Punch Communications - PR Agency Homepage / Punch Blog / Twitter / Linked In

Punch team Twitter details: Abbie, Ben, Claire, Christie, Katharine, Pete, Philip