Have an option to keep only a certain number of tweets or keep only for set number of days. Currently when logging in after a week or longer the number of old tweets slows things down and crashes the site. I only need to see recent tweets so keeping 10,000+ old ones isn't necessary.

I'd like to be able to view my twitter "saved searches". I'm planning on setting up a filter, but I don't currently follow everyone that uses the hashtags I have on saved searches.

I'd like to see which other accounts have RT'd either a tweet I've RT'd, or one that I've posted and others have RT'd.

When I create multiple filters, which all point to the same folder, I'd like to be able to see which filter sent the tweet to the folder. Some sort of hover action that gave the filter name would be good.

I want to be able to RT a tweet I have posted from one account I own and have connected to tweetdig, using another account. (eg; RT a barcampblackpool tweet, using my personal lallyd twitter account)

I'd like to be able to drag/send a tweet into a folder from my timeline, without it affecting any filters.

Instead of having to select the account to tweet from, if I click on compose a tweet when I am in a selected account inbox/timeline it should automatically assume I want to tweet from that account and highlight it as appropriate.

Instead of clicking on folder options to get to mark all as read, I'd prefer it to be a button on the dahboard so it's quick and easy to access when I'm returning to the site after a few hours of being away and my unread count is high.

So when I type in the username when creating a filter (or composing a tweet) and the user I want is the top result, I can tab to complete that username rather than having to click on it.

I'd like a button that takes me to the top of the folder without marking all the tweets as read, so I can read the most recent tweets first, then decide if I want to go back to read more or just mark the remainder as read.

I'd like to be able to reply to a person publicly, without using the reply button threaded to an existing conversation. At the moment the only way to do this seems to be to compose a new tweet and type in their username, but I'd prefer to be able to click on their username and use a "send this person a tweet/dm" type button.

I want to be able to see at least the last few (10-20) mentions a person has received. Regardless of whether or not I follow that person.

In the first instant, filtering based on a list (yours or one you follow) would be really handy.
It would also be great if you could add and combine multiple lists into one stream and remove duplicate tweets e.g. I may have a tech-people and a manchester list, with some common people. I think only TweetDeck on the desktop does this currently

Say I create a filter called "indie devs" and want to add a new person to that filter. Rather than editing the existing filter and trying to remember obscure twitter usernames, it would be nice to have a "add to existing filter" button.

TweetDig will update new tweets automatically and not just every 20 second. Like the official Twitter app for Mac and Tweetbot

I'd like to import twitter lists and then filter them.