Lets try to gage interest and find something nice.
The act of fixing little things that are seemingly irrelevant and not obviously broken for the greater good of visuals that are uniform and make sense.
Done right its beautiful, done wrong it looks actively ugly.
This process starts at the ordering and information stage,continues with out of the box experience. And finally, and most importantly, the little improvements to make the device pleasant to use.
OS:
Debian jessie 8.0 with
DE: Xfce 4.10 or 11. Everyone can help translate Xfce to their language now
https://www.transifex.com/organization/xfce/dashboard
Moonlight or
Lxqt possibly LXDE These are qt(5) rather than gtk+ based
etc...
DE: XFCE please, also XFCE devs are quite unforgiving on supporting older releases. It has many ligthweigth apps written for it. (i generally prefer gtk+ apps for lightweight)
Image viewer: How about Risretto instead of PIV ?
Image manipulation: Yup, mtpaint (gtk+) is nice,small dev-minded pixel tool! Also RGBpaint is really small and fast, kind of like MSPaint. Kolourpaint is a bit bigger, looks a bit more like Paint.NET.
Video editor: Is this the right platform to edit videos on ? It requires a lot of motherboard troughput, not to mention CPU/RAM.
File manager: I actually prefer Nautilus over Thunar, it has more tools/app support made for it too.
Terminal emulator: I'd just use Terminal from XFCE. It has multitab and a usable GUI. But if we're doing KDE runtimes, let's do Konsole!
Editor: I prefer SciTe over Mousepad. They are abut the same size and speed, and SciTe is the better dev editor and also has project plugin.
Development: Codeblocks is nice but quite heavy, may I suggest to add Kate as an option? That's real good as a IDE/project manager with sessions and plugins.
Office suite: I think that all the office suites are too big! Also, they can not usually not be removed without removing the entire desktop ecosystem. Please make this optional.
Spreadsheet program: GNUmeric?
More dev tools: Lybniz (graph plot tool), GTHhash (checksum app), Bless (hexeditor), Meld(merge tool), Kompare(diff tool), SVN Workbench and SQLite Database Browser?
More accessories: BleachBit (essentially CCleaner for Linux), Filelight (diskspace analyzer), KeePass2/KeePassX (password manager, former uses Mono libraries. Needs the xdotool package also.), GNUPG with KGPG (PGP functions from context menu, think it works in Nautilus out of the box)
More network: kVIRC (IRC client), putty, gFTP, Electrum Bitcoin client (lightweigth, does not download the blockchain), Pan ( newsreader) , SecPanel
Edit:
Console network tools: screen/screenie (console multiplexer)
Console compression tools: lhasa lzip lzop ncompress rzip sharutils unace unalz unrar p7zip-rar zoo ziprecover plzip
Also, an out-of-the box working Samba browser client to connect to Windows shares with would be killer. (practical to copy ROM's and other media with real quick)
My 2 cents !