dvd-slideshow can create flash video content. Then, you can easily add the content to your web pages and so on.
This is how all the videos are generated for this wiki, for example!
dvd-slideshow -flv inputfile.txt
also, you can try the new output size option:
dvd-slideshow -flv -s 320x240 intputfile.txt
Note: There may be some bugs still when using -flv and low quality mode (-L)... Hopefully it will be fixed soon.
Specializing in formats meant for portable devices, FLV Converter also supports.
Mac FLV Converter which can convert FLV video for Mac with editing functions.