Over the weekend I installed GO Launcher EX on my Kindle Fire.
GO Launcher EX is a replacement UI many Android phone users are already using. If you are not a fan of the shelf style UI of the Kindle Fire, this may be an option for you. GO Launcher EX works well, but it does have some glitches on the Kindle Fire.
It's a minor hassle to get installed. If you're happy with your Kindle Fire experience, you really don't need to do this. :-)
You'll need to get a 3rd party app store on your Kindle Fire. GetJar is one of the few you can install without having to root the Kindle Fire. Rooting is a hack to unlock the Kindle Fire's android OS to allow 3rd party apps and settings. This is similar to jailbraking your iOS device. I'm hesitant to root the Kindle Fire because you risk crippling it, preventing it from updating via Amazon, and you may even void the warranty.
Visit GetJar.com with the Kindle Fire's web browser and install their app store. If you can't find how to install it, just Google search for help. Remember many apps at GetJar, may not run correctly on your Kindle Fire. Most of these apps are designed for Android Phones and not the Kindle Fire's tablet version of Android. Installer beware.
GO Launcher EX is available in the GetJar app store.
It's not perfect and obviously it's not designed for a non-phone tablet. Still it's a much better UI for app management, and you'll be able to use many of those Android app widgets that make the Android OS unique. Those of you famailar with an Android phone or iPhone will feel right at home in the GO Launcher EX environment.
There are a few issues that I haven't found a solution for. One is you can't access the Kindle's book or magazine readers from GO Launcher EX, you have to use the Kindle Fire's Launcher. And another the wallpaper won't save (annoying). When you relaunch GO you end up with what ever wallpaper the Kindle Fire's lock screen was using. Which really isn't that bad, some of those pictures make great backgrounds. There may be other issues I haven't come across yet.
If you don't set a default launcher, when you click on the Kindle Fire's Home button, you'll be prompted to select which launcher you would like to use. This is really handy when you switch between environments.
Watch for updates to GO Launcher EX. I installed the latest update and it improved things greatly. The flow and navigation works much better. (It's still has those issues I mentioned above).
I'll keep posting updates over a Google+ on my experience with GO Launcher EX on the Kindle Fire.
Update: I just found out about GO Launcher HD which is designed for tablets. I don't know if it'll run on the Kindle Fire or not. It requires Android 3.0.