I noticed one annoying thing about Gmail for me. I always had to hit the big "Display Images" button to view emails properly.
So I decompiled it, did some editing, and got it to always display images period. Doesn't ever show that big ugly button either. All emails load images, it's great.
This is based on the latest FROYO Gmail. I may make a version for Eclair if there's enough people interested.
You will need to be rooted.
Method 1: adb push Gmail.apk /system/app
Method 2: copy Gmail.apk to /system/app using Root Explorer
Delete Gmail.odex from /system/app if it exists. Also delete GoogleMail.apk and GoogleMail.odex if they exist.
You may be able to simply uninstall the updates to Gmail and then install this like a normal app, it may not require root. Someone try it.
apk is attached