This is not an add-in but I assume we can write about other Media Center related applications as well and this one just has to be on the list!
ngRC-next generation Remote Control is one of my favourite MCE applications ever. I use it alot and version 2 is a massive improvement on the previous version, although that was great as well.
I use this on my Sony PSP to mainly control my music playback on the Media Center PC whilst sat in the garden. I can add albums to the queue I can browse the music library by genre, albums and artists etc. The virtual remote on this thing is excellent for adjusting the volume, pausing music playback, skipping tracks etc.
This is a freeware application written by a very talented guy called Oliver Schulze. You can find his webpagehere.There are some bugs and issues with version 2 but it is still in beta, I know Oliver is working hard on the issues already raised to get them resolved. However that does not detract from the fact that this is an amazing piece of software and is a must for any MCE user.
The software is web based on HTTP meaning it runs in the browser, so it would probably work on a wide range of portable devices that have browsers on them. Give it a try and help with the development by submitting your feature requests and bugs to the developer on his forum.
turn your iPhone/iPod touch or your PSP into a cool WiFi remote control. ngRC gives you the abability to control your VMC/MCE (Vista Media Center or XP Media Center) and all your connected extenders with only one remote control.
But controlling your media center remotely is not the only thing, ngRC is able to do. Do you want to play music from your library, without switching on your television? No problem: ngRC enables you to browse through your complete music library, play music, add to playlist, etc… So you can stay in your kitchen and choose another song, that should be played, without the need to walk to your TV in the living room. Even if you want to play another music on your extender in another room, just switch ngRC to that extender and choose the wished music there…
And the best: ngRC is completey free of charge.
Here is a list of features of ngRC:
Full feature remote control (replacement for IR, let you control your media center over WiFi)
Useable on all iPhones, iPod Touch, PSP, PC, Tablet PC (everything that is Browser-Capable)
Extender Support (control every extender from every room, with only one remote control)
Music-Library-Search (Browse your media center music library by Album, Artist, Playlist, Genre, Title, view Album Details, Title-Details, etc…), filter music by keyword.
Play selected music
Add selected music to playlists
Show actual playing title
Show actual playing playlist
Nice Covert-Art display (mirror-effect)
Direct Jump from Home-Screen to TV Guide, Recordings, Pictures, Videos