Joel16 has updated his Shell app for the Nintendo 3DS:

This is a major release. If you're updating this from an older version, it is recommended to delete your /3ds/3DShell/ folder before you install this update. This is to prevent cluttering up your SD with unused data files from previous versions.

Now uses Citro2D for handling graphics, along with many other optimizations and improvements.
Music player now has the ability to play next/previous tracks using L/R or Left/Right or touch.
Music player now has the ability to shuffle/repeat tracks.
Added sleep mode support for music player.
Added online updater. (Nightly builds - builds per commit, or Maintainer builds - stable release versions only)
Image viewer now has ability to use L/R or left/right buttons to navigate next/previous images.
"Move/Cut" option is now instantaneous instead of copying and then deleting.
Added multi-select for delete, copy and cut. (Use 'Y' to multi select items)
Added support for Nintendo (both screen) screenshots in image viewer.
Added support for Nintendo camera images in image viewer.
Added support for wallpapers up to 800 * 480. (Some images may appear badly stretched due to the dimensions - but that depends on the image)
Displays GIT version instead of compile date.
Buttons can be used in navigating options and settings. (Does not rely on touch screen only anymore)
Now displays file size and modified date/time in properties.
Use left/right to reach start/end of directory list.
Removed theme support. Now only has a dark theme toggle in settings. (Due to lack of community participation the theme engine has been removed entirely)
Minor revamp of music player. (More similar UI to eleven music player)
Removed gallery bar, recycle bin and system protection. (Poorly written/unappreciated features)
Fixed crash when pressing home or trying to exit while FTP is on.
Fixed sleep mode bug when playing music which led to a blank screen once the lid is back open.
Many under the hood changes to improve performances and stability.

If you'd like to support me, then feel free to buy me a coffee, I'd really appreciate it!