Is there a chance that some day with your help games that you redistribute will start to evolve( considering that you have source codes of the redistributed games). For example there is a clone of WarCraft2 - Wargus, with more convinient interface. Maybe this will become possible if the games will start to bring a good income. Maybe income will grow if more people in the world will know about you. Maybe more people in the world will know about you if you'll do something unic, like porting games to all popular platforms, like PS[X][2][3][P][Vita], Android(for tablet computers), Mac(I count mostly on the mobile devices)(Mostly on PS[P][Vita], MacBook, Android(for tablet computers)).

Unfortunately, GOG does not have access to source codes.

That's a glaring misapprehension you've got there. In the vast majority of cases (possibly all), GOG does not have the source code for the games they distribute.

Edit: Ninja'd!

Right and for many (most?) of the games the source code doesn't even exist as the industry is terrible at preserving it's own history.

Sorry for my ignorance, but how do you fix games, to get them to work on modern PCs? And how do you port a DOS games to Windows?

DosBox. But it is not a port but an emulation.

Whats the difference(in bytes)(except for bonuses) between original games and games from GOG.COM?

All sorts of workarounds, really. Various wrappers. ScummVM and DosBox are a godsend for GOG. Sometimes even old cracks and fan patches. It very much depends on the game in question.

You must go through an awful lot of sacrificial goats ;-)

There a select few games for which source code is already publicly available. I know the source code for the Build engine has been released (making ports of Duke Nukem 3D and Blood possible), and Arkane Studios released the source for Arx Fatalis, so a port to Mac and Linux at the very least is possible.

Until a few years ago, the archiving of source code was a rare thing indeed. A number of companies did it (id, 3D Realms) but I think that was only because they made licensing their tech a major part of their business. It's a fairly recent phenomenon that devs keep their source code indefinitely since the more long-term exploitation of IP has become profitable.

They do the work themselves, the bigger issue tends to be licensing. Once they have a license it's some times trivial to make the game work.

I'm not sure what advantage bringing in other people other than to patch DOSbox bugs and fill holes would represent.