If you have more than one phone, or more than one android device (i.e a phone and a tablet), you may find it annoying that your SMSs are not synced between devices. More-so, if you have a tablet, it is likely that you can not send an SMS from it at all,
If this sounds familiar, then Sync SMS is the app for you. Through utilising a dropbox account (which you must have in order for Sync SMS to work), Sync SMS will keep your messages synced between all your android devices, and also allow you to send messages from any device.
Of course, you will require your tablet to be connected to a wifi network, and you will require the app to be installed on both your tablet and your phone, but if these pre-requisites are met, and with a bit of tinkering of settings, you will find yourself being able to send and receive messages no matter what device you have in your hands.
In the words of the developer:
SyncSMS lets you sync your text messages between your Android phone and tablet.