The thing I most miss about the Java based BlackBerry's is decent Twitter apps - I really wish there was a Twitter app for BB10 that was as good as T4BB or one of the other choices, or as good as Blaq for the PlayBook. A close second to that though is theming - I was very disappointed when BlackBerry decided not to launch Theme Builder for BlackBerry 7, and far more disappointed when it was announced that there would be no BlackBerry 10 Theme Builder.
A small amount of customization can be contrived using apps like my recent Z Theme app, but that doesn't let you modify the device icons. However, there is a way to create a shortcut for many of the existing applictions. For a more in-depth explanation of how these icons work, read this CrackBerry Forums post.
Creating your Custom Icons:
Step 0: Get BlackBerry Signing Keys and configure your PC for signing.
Step1: Download the templates from my Github: https://github.com/SCrid2000/BlackBerry-URI-Builder, and copy the templates you'd like to use into a folder on your desktop.
Step 2 (optional but recommended): Set up the signing tools. To make this easy, I have provided downloads for all needed signing tools. Get the signURI.bat and sideloadFile.bat files from github and put them into a folder with the signing tools contained at http://www.mediafire.com/?qq64yck165xtbwc.
You'll need to open the .bat files with a text editor to add your Signing Key Password and BlackBerry IP/password to them.
Step 3: Get the icon you'd like to use. Resize it to be 114x114 pixels, and place it in the folder with the META-INF folder.
Step 4: Modify the MANIFEST.MF of the launcher you'd like to create. You will need to modify the following:
Package-Version: must be increased by at least 0.0.0.1 for each successive signing;
Application-Version: must match Package Version;
Archive-Asset-SHA-512-Digest: does not always need to be updated, but sometimes might cause signing to fail. Use a site like http://hash.online-convert.com/sha512-generator to get the appropriate SHA-512 hex for your image.
Other attributes can be modified if you'd like, such as Application-Name, Entry-Point, and others. However, this is unnecessary if you just use the templates included in the Github link above.
Step 5: Compress the icon.png you created and the META-INF folder containing the MANIFEST.MF file into a .zip file. Change the .zip extension to .bar
Step 6: Sign the URI by dragging it onto the signURI.bat
That's it! Just do that for any icon you want a custom icon for, and sideload it to your BlackBerry!
Keep in mind that these are shortcuts, and will not replace the stock icon.
Co-founder and legal nay-sayer of OSBB. Owner of SCrApps Application Development, WebWorks aficionado, Open Source contributor. SCrid2000 on most blogs. I build awesome BlackBerry apps when I'm not doing legal work or spending time with my wife and two boys.
Follow me on Twitter - @GShaneC
Check out my apps in BlackBerry WorldWebsite: SCrApps.org