I've changed my e-reader and i want to convert my .lit files in other supported formats (AZW, TXT, PDF, HTML, DOC, DOCX, JPEG, GIF, PNG or BMP)
Calibre is what you are looking for! It can also handle your whole library.
Now you can convert your books into other formats, readable by your new e-reader:
Play around with this little piece of software, try different settings, etc.
This only works for non-DRM eBooks!