I have tweaked the stock keyboard and added a number row. I did remove secondary long press for keys. I'm sure some people wont like that but I never use that and it makes the keyboard look cluttered. I'm not really planing to add features but the below instructions will help you add more tweaks.
Instructions: (Non-Samsung based ROMS)
- You obviously need root access.
- Download LatinIME.7z
- Extract file. You should now have one apk (LatinIME.apk)
- Make backup of system/app/LatinIME.apk.
- Copy the apk to system/app folder.
You guys can do this also with these instructions