MobiReg
This is small registry editor which supports supports creating and editing of string, binary, DWord (32-bit), QWord (64-bit), multi-string and expandable-string data types. Additionally to that, there is support for both Smartphone (Windows Mobile Classic) and Pocket PC (Windows Mobile Professional) platform in single executable.
One of features that may help you to decide whether to use it or not is support for both import and export of registry in standard .reg file.
To use this program you need .NET Compact Framework 2.0 installed on your machine.
NOTICE: There were few reports about program causing deadly reboots on HTC HD2. I still cannot reproduce it but, just in case, I would advise against installing it.
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Program requires .NET Compact framework 2.0 (or higher).