http://www.wotsit.org/ has many file formats documented, and is a good place to start.
Some formats are proprietary, meaning there may be little or no information in the public domain.

You could also try "ttf file format" as a specific search, to locate other examples.

Thanks. A lot of it went over my head, but it's a nice resource to have.

If you're under Windows, you don't need anything.
The Win32 api does it automatically.

The Win32 api can convert .bmp fonts into .ttf file?

Is bmp font == pixel font? If so, I think it's impossible automatically convert pictures to True Type font. The last one is not only character glyphs but really a special program for rendering fonts with different rasters and sizes. There are tons of utilities (of course, libraries too) which are capable to convert ttf (and other outline) fonts to pixel fonts, but I never heard about automatic reverse direction transformations.

On the other hand, numerous font generators and editors are capable to import pictures as a base for interactive ttf font design and improvement.

Slightly obsolete but interesting link on this topic:
http://nwalsh.com/comp.fonts/FAQ/