Big Note is a very simple plug-in that adds a big note field to the Metadata panel. You can store any text in the field, and it can also be searched by smart collections.

Any information entered in the field is stored in the Lightroom catalogue. It is never written to the images’ XMP files and is not included in files exported from LR. That’s because Lightroom doesn’t yet permit a plug-in to use its XMP-writing engine, and it’s one reason why I have big reservations about how custom field metadata is handled in LR2 and LR3.

I have therefore left the metadata definition and panel unencrypted so anyone who can hack Lua can modify these files.

It’s free, unsupported, but should do the very limited job it’s designed for. Try it first on a test catalogue.