The original Mount & Blade (not Warband) is being given away for free at GoG as a promotional hook for their 2014 DRM-Free Big Fall Sale. They could do with a catchier name for that sale, I think. Nonetheless, it is correctly labelled a “big” one, offering more than 700 games at a discount.
To get Mount & Blade, you’ll need a GoG account. Once you’ve set one up, look for the free game offer about halfway down the main page. Log in, press the big FREE GAME button and GoG will give you a message saying an email will come through once Mount & Blade is added to your account. Took about 10-15 minutes for me.
It’s not quite as good as Warband, lacking the multiplayer aspects and one of the factions (plus the ability to set up your own, I think,) but it’s not at all bad as a free gift. Mods these days tend to require the Warband version too, but hey.
You have until 14 November at 1.59pm GMT to claim the freebie. That’s about another 38 hours from the time of writing.
If you fancy other titles in the Mount & Blade series, they happen to be on sale in a daily deal as part of this whole event. The other current daily is an Ultimate D&D Collection for $21 USD (down from over $100 USD) which includes such Black Isle classics as Planescape: Torment and Icewind Dale, the inevitable Baldur’s Gate and sequel, plus others like Troika’s Temple of Elemental Evil.
There are far too many more to list in full, so have a browse around of GoG’s site. If there’s something from their catalogue you fancy, chances are it’ll have some money off at the moment.