It’s been a month since the last update on new and existing modifications.
The existing ones have been upgraded and improved, take a look at LaurentG’s mod and juliojs’s work (or his blog (spanish)).
Regarding the non OSD mods, ninja76’s torrent downloader has also lift off and makes progress. realtebo’s IRC download client is also there but hasn’t had any updates lately.
Regarding new developments there is a thumbnail cache from BMD_Online that speeds up when you are using the thumbnail view to browse your media.
Probably the most exciting latest development is pibos WDTVExt project. He has actually managed to tap into the WDTV GUI to modify the main menu and enable new plug-ins. There are already some examples like a weather plug-in.
There is also a very good new OSD Mod from lilibabe, very slick design:
There is ton more but most are basic extensions for WDLXTV or very specific applications. A more or less complete list is managed in the forums at http://wdtvforum.com/main/index.php?topic=1217.0.