While they aren’t as fully-integrated as how Siri is with the iPhone 4S, most of them are touted to be just as useful. Pannous’ Voice Actions happens to be one of the apps in this category. While I have yet to try it out, it does have an impressive feature list that sounds like what Siri can do. Send emails and texts, set alarms and reminders, answer your voice based questions and searches, voice dial your contacts, translate your spoken words/sentences and more.
Unfortunately it’s not free ($6.99) but hey – that’s much cheaper than forking out the money for a 4S just for Siri, right? Check it out on the Apple App Store if you’re interested.