Firstly, thank you so much for such a quality application for GNU/Linux.
The feature I would like to see included in Synfig would be the ability to save the animation also as .mng (Multiple Network Graphic), the motion cousin of .png (Portable Network Graphic). MNG serves as a open, free alternative to animated GIF and it has more than animation (please refer to ) and I feel Sysfig would be great a software to promote a great format like MNG.
Right now there is also a thread at Mozillazine,  , on persuading Mozilla to restore support for .mng back in Mozilla Firefox. For the time being there is an extension for Mozilla Firefox to play .mng animations.
Gimp supports .mng out of the box for both playback as well as conversion. Gimageview has support for playback.
--Zaheermk 14:00, 29 Dec 2005 (PST)