Speaktoit, which first launched on Android, performs many of the same tasks as Siri, allowing users to search the web with their voice, and pull up maps for directions. It also packs some of the same personality as Siri, answering humorously to many peculiar questions and requests.

Apple didn't enable Siri on any device other than iPhone 4S, citing a need for a certain amount of RAM and processing power for the software to run properly. Speaktoit, however, will run on any iOS device running version 4.0 or later, making it a worthy alternative to Apple's home-grown virtual voice assistant.

Interest in voice-enabled software assistants is growing since Siri's high-profile introduction with the iPhone 4S. The Android platform offers a few possibilities, such as Iris and Google's own "Majel" initiative, which aims to bring voice-recognition capabilities to future Android devices. The technology will reportedly upgrade Android's "Voice Actions" app, which lets users make calls, get directions and perform searches on Android smartphones using voice commands.

The Speaktoit app for iOS sells for $2, and although it will not feature the same integration into iOS as Siri, it could be one of the best options for users of the iPhone 4 and 3GS.

Speaktoit also has some features that Siri lacks. Apple has gone out of its way to say that Siri is still in its beta phase, and Speaktoit outshines the 4S's virtual assistant in a few areas. The app allows users to post directly to Twitter, Facebook and Foursquare with simple speech commands and is also compatible with very popular Evernote app.

If you tell Siri you want to tweet something it will respond "Sorry, I can't help you with Twitter," and asking the software to post a Facebook status will yield a similar response.

In addition, Speaktoit has customizable avatars that users can talk to and can search maps all over the world rather than just inside the U.S., like Siri.

Speaktoit will likely be downloaded mostly by iPhone 4 and 3GS owners, but for 4S owners who want to post to social networks with their voices, it is likely worth the $2 price tag.