CIO — Twitter had a big year in 2009: It announced several partnerships, including one with LinkedIn. In September, Twitter was valued at $1 billion. And most recently, "Twitter" beat out "Obama," "H1N1" and "vampire" to be named word of the year by the Global Language Monitor.

Twitter also rolled out several new features, including lists, geotagging and the controversial retweet function. But users are increasingly abandoning Twitter's site for Twitter clients like TweetDeck, Seesmic and Tweetie, according to research from Dan Zarrella, author of The Social Media Marketing Book. These third-party apps tend to allow more control over the display and include more features. Here are five features I'd like to see from Twitter in the next year.

1. Threading tweets. Ever propose a question to the twittersphere and receive multiple responses? That's generally the point, right? The current interface only allows you to view @ replies in a list, which can be confusing if you're trying to follow a conversation. Displaying these replies in a thread could alleviate that, and even encourage more participation.

2. Delete-all function for direct messages. Not too long ago, Twitter users were slammed with spammy direct messages asking you to "check if your IQ is higher than mine!" or informing you that "I think I found your high school photo here!" Annoying automated messages you receive after following someone also clog inboxes, but manually deleting each one takes too much time.

3. Group messaging. Twitter was on to something when they rolled out lists. I'd love to see a capability similar to lists, but one in which you have the ability to opt-in, send and receive messages to or from a group. For example, if you wanted to poll a group of your followers interested in Windows 7, you could do so without bothering your devout Mac-user followers.

4. Receiving notifications of @ replies. Twitter gives you the option of being notified by text message or e-mail when you've received a direct message, so why not offer the same capability for the more-public @ replies, too?

5. Better search capabilities. Searching through past tweets for that one post you remember sharing—especially when you've accumulated hundreds or thousands of posts—is nearly impossible. I'd love to see the capability to search your tweets by keyword or date. The same goes for searching your followers: Currently, contacts are listed according who you most recently added. Even an alphabetical listing would be a step in the right direction.

What would you like to see from Twitter in 2010?

Staff Writer Kristin Burnham covers consumer Web and social technologies for CIO.com. She writes frequently on Twitter, Facebook, LinkedIn and Google. You can follow her on Twitter: @kmburnham.