Swype, the handy keyboard replacement that thrives on other platforms (most notably Android), has been ported to work on jailbroken iOS devices by Andrew Liu (@wyndwarrior). You can get Swype by downloading it from here, and then SSHing it to your device and installing through iFile.app. An easier alternative would be to add the following repo from Cydia and download/install from there: wynd.x10.mx/repo
Andrew does warn that the package is still in beta, and that it won’t work with many apps (Mainly apps from the App Store; although he does say that a fix is coming soon for that).
After you install, be sure to respring your device.
