Sounds Bad, But I use Steam as a Launcher for my games.

For Windows games it's easily set-up, for dos it's also easy, if you remember how to start dosbox from the command-line

First things first, It's GOG, not GoG.

The downloader kinda doubles as a desktop app in that it informs you of forum replies, game updates, and downloads complete. However it doesn't have a "Library" section. It would be tricky to do so given that the games are not very traceable, as they're DRM free.

You could add them to steam, if that would help? If not there's probably an open source catalog app I could have a crack at adapting if you wanted (need to test out my newly repaired hands, see if they work, so would be happy to try).

They should also release applications for Windows Phone, Windows Runtime, Android, iOS, and OS X...

... also improve the current web offerings by adding more features, list the games in Windows Store, update old releases with the latest fixes and versions of included software packages...

... but hey, let's do the 'vote in the wishlist' thing and hope somebody notices.

(that vote in the wishlist reference was a joke, they should instead work on improving what they have to offer every single day, though I doubt we'll see new stuff soon)

Something else I now Remember is D-fend Reloaded. It's Mostly for Dosbox, but One can start Windows games from it
:http://dfendreloaded.sourceforge.net/

If it's a matter of being tidy and practical why not just put all GOG game shortcuts into a desktop folder? Make it display them in a list and you're set. If it's about looks then I'll have to agree with the people that told you to use Steam.

Doesn't have to be all too tricky if one relies on the registry entries that the GOG installer makes (and those who are knowledgeable enough to install the games in another way likely have little use for such a launcher).

I don't have the energy to sit and experiment with the idea at the moment, but if you make the assumption that said entries are available and correct, you could use those to make a list of the games and figure out the games' launch path, and then use the 256px icon from gfw_high.ico in each game's directory to get nice box art (at least more visually interesting than just a line of text saying the game's name).

My suggestion:
Create a folder somewhere you don't mind making folders, name it something like Games, put all the game shortcuts in there, then right click your taskbar, Toolbars -> New Toolbar -> browse to your Games folder, select it. You now have a folder that you can open either as a popup list or as an explorer window. Open the folder once through the new taskbar thing (right click, open folder), switch the view to Extra Large Icons, and it'll be like an album view. It'll remember the setting for that folder, but won't apply it to others.

Attached an example of what it could look like, in both views, and resized it because I have a thing with trying to keep image file sizes down when uploading 'em here.

i would love a nice little gog app like steam has with a library and some social features thrown in