Some new homebrew that isn’t a backup manager or an emulator — this is andoma’s Showtime media player for HTPC media centers. Me, I use the DLNA/UPnP-enabled PS3 Media Server (on Linux) and the GameOS provided features to display video, play audio, etc… but I understand your setup/tastes may differ, so for the HTPC folk — it’s Showtime!

Feature overview
- Playback of video and audio
- Javascript plugins
- Unified search
- View photos and images in slideshow mode
- Live TV streaming from Tvheadend
- Spotify integration
Showtime can also browse and play audio/video from the local PS3 HDD and other UPnP media servers. There are other features that may be of interest to you, so I reckon you check out the source link for all that. And as far as MKVs go, I’ve read mixed reports; not sure if they’re playing from the local HDD or if transcoding via your media server is still the way to go.
Download: Showtime Media Player