Writing my first cover letter for a journal article today - my PI's always taken this on before.  I basically had no idea of what to write.  So, using the magic of google, I found some cover letter examples that other people had made available.  And thought I'd pass on the love.  It comes from a blog called Science for all.

And once I've decided if my effort is any good, I'll post it and give people another version to get ideas from.