Personal assistant apps using voice recognition technology have become very popular over the last few months. With the ability to send email, buy movie tickets, learn about your community and much more—all just by speaking to your phone—it’s easy to see why.

Voice recognition has been around a long time, going back to the Microsoft Windows® mobile platforms and the old PDAs, says Kevin C. Tofel, mobile editor for GigaOM.com. Today’s renewed interest results, in part, from improvements in the natural user-interface that make for better recognition of normal speech; it also has much to do with the development of the cloud, which enables the necessary processing.

“Anytime you’re using any mobile app that uses voice recognition, chances are that it’s sending your voice recording out to the cloud,” Tofel says. “Most of the processing is happening in the cloud—that’s why you need a connected device.”

If you’re using an Android phone, you may already have Voice Actions, allowing you to dictate texts and emails, play music or show a map through voice commands. Turn on the personalized voice-recognition capability through the Settings function, and Google will learn how you speak and improve its responses. (One note: you don’t need to speak exceptionally slowly or over-enunciate, but do try to avoid a lot of stops and starts when you speak.)

Voice Actions does have limits, though (it won’t update Twitter, for example, and complex commands may not work), so new apps are springing up to refine and expand voice-recognition functionality. A few notable choices:

This app “makes witty remarks and even tells jokes,” say developers. It also performs searches and offers Twitter and Facebook integration—it can update your status or read aloud your best friend’s wall. Skyvi can give you directions, weather information and reminders, but it doesn’t make calls or send messages. You have to tap the mic button to turn on the app.

When you launch Speaktoit Assistant (using the mic button or a long press of your phone’s Search button), you’ll see your assistant avatar, which you can personalize if you choose. Your assistant answers questions, creates messages (you’ll still have to hit Send), adds events to your calendar, initiates calls and shows you the nearest coffee shop; it is integrated with Twitter, Facebook and Foursquare. “It’s conversational, and it does that by context,” Tofel says. Ask, “What’s the weather like in New York?” and then ask, “What’s it like in L.A.?,” and it will know you’re still talking about the weather. It also has a Conversation Mode; once it’s enabled, you don’t have to hit the mic button each time you speak. Your assistant automatically prompts you for replies.

Vlingo’s Virtual Assistant app can send emails and texts, search the web, place calls and launch apps (but not give commands inside the apps). “It’s very step-by-step,” Tofel says. “It’s designed to get quickly at tasks without a keyboard.” It has a hands-free mode that lets you launch the app then put the phone down and speak to it; it will make sounds to let you know it’s listening and processing your commands. But if you’re asking it to do something like write a text, you’ll still have to pick up the phone to hit Send. The app is available on Android, BlackBerry and Windows.

Tofel describes Jeannie (previously Pannous Voice Actions for Android) as more conversational than others. It performs many different kinds of tasks—initiates phone calls, searches the web (not just Google but specific sites such as Amazon and Wolfram Alpha ), sets your alarm, controls other apps, plays music and translates; it can answer your questions in several languages by text (only in English by voice). In Settings, you can find a list of its features (or you can just ask “What can I do?”). A faster, and ad-free, Pro version is available for $2.99, with a beta “listen in background” feature.

Are you using a virtual assistant/voice recognition app? If so, which is your favorite and what tasks are you using it for?