bill said:

I have recently bought a Kindle and down-loaded quite a few books. I have scanned and part-proof-read my copy of John Buchan's 'Castle Gay',

first of all, bill, welcome. i've been waiting for you -- waiting for new kindle people to begin uploading books that they converted initially for themselves -- like people in san juan capistrano await the swallows. so i am glad you've arrived... :+)

I have a number of other John Buchan books that I could work on, but is there any point?

yes. indeed, even when a book has already been done, it's great to have a second digitization, because then the two versions can be compared, a process that has been proven to be the best way to reveal any _errors_. (while it may seem, intuitively, that it could be common the same error is made in both digitizations, empirically the finding is that it's exceedingly rare to have it happen.) so if you _enjoy_ doing digitizations, go ahead! (of course, you might find it more satisfying to do a book that's never been done, rather than improve a book that somebody else has done. but there is great value in both those activities.)

A secondary question: can anyone recommend a way of converting my stuff into Kindle format - I run Ubuntu Linux, but so far have found only software to read Kindle format.

i see that you've received recommendations to use the project gutenberg software, as well as calibre... i encourage you to explore both of those options... i find the p.g. workflow to be unnecessarily obtuse; and the markup from calibre can be terribly opaque, meaning it's very difficult to change, when you need. so i would also encourage you to explore my option: it's called "jaguar", and it's available at this website:

http://jaguarps.com

that's the initial release, and i'll be uploading a new version "any day now", but it will give you the flavor. (and i'd love to have a beta-tester for the linux app.) from a plain-text file, very similar to the one which you get from your o.c.r. app, you can create a raft of e-book output formats: pdf, html, epub, and mobi. all of 'em in just seconds, with the click of a button. my system gives you an easy way to _customize_ the output which is generated for these various formats. why shouldn't your e-books look the way you want? single-source plain-text "master" files are a smart way to manage a library and customize your output. -bowerbird