Luckily for me, with Android, if there's a will, there's an app. TexTab connects your Dell Streak 5 with any other Android tablet via Bluetooth, and allows you to send and receive texts on your larger screen. Just open up the app on both devices, send a text, and go!
Unfortunately, the app isn't perfect. I found it confusing at first to connect the two devices — you have to put the tablet into the app's "tablet mode" and the phone into "phone mode," and then make the phone discoverable and press the discover button on the Tablet. It's straightforward once you've figured it out, but the app doesn't do a very good job of cluing you in on connecting them.
The only other issue I can think of is that the devices are connected via Bluetooth. When you open the app, it is able to turn on Bluetooth for you, but doesn't offer to turn it back off when you exit it. This can lead to accidental battery drainage, as leaving Bluetooth on is known to be detrimental to battery life.
Other than that, the app works great. It even works on Dell Streak 7s that haven't been updated to Honeycomb yet, so anyone with a phone and a tablet can get in on the larger screen texting action.
Anyone who wants to try this app out can grab it at the link below. You can also check out the lite version, if you just want to test the app before making a committment.
Links: Market (Streak)| Market (web)