If that's about messagebox font, check
jh_fallout-webfont.*, originally used on
ServerBoy by
CptRookie.
As for other fonts FOnline uses, i don't think there are .ttf versions - at least i couldn't find any which will be exactly same as ingame. If you're fine about generating images with your text, i wrote
small php class for automating the process. It can read any .fofnt file [version 2] as well as colorize the output.
$font = new FOnlineFont( 'path/to/file.fofnt' );
$image = $font->TextToImage( "Hello world!" );
$image_color = $font->TextToImage( "Hello world!", 255, 51, 153 ); // Wild Strawberry
Note that FOnlineFont class is extremly paranoid and will die() on first spotted error; if you're not sure if given font contains all letters in your string, validate it first.
$text = "Hello world!";
$font = new FOnlineFont( 'path/to/file.fofnt' );
$image = NULL;
if( $font->TextValid($text) )
$image = $font->TextToImage( $text );
else
$image = your_function_to_generate_error_image();