This has been doing the rounds through USA users of Microsoft services and now seems to be available more widely, but.... just in case you haven't already seen this offer from Microsoft for 100GB extra of OneDrive space for two years, try clicking this link. It seems to be linked to 'Bing' in some way - my guess is that it's just Microsoft's way of getting more people onboard with OneDrive in a big way - at the end of the day, it will all be about head count on each platform and upselling users services and applications....
The link worked for me, by the way. Here's my adjusted OneDrive:
What with the Office365 OneDrive giveaway (though at least Microsoft gets the Office subscriptions), plus Windows 10 being given away for the first year of upgrades, Microsoft is certainly in generous mood. It's all part of a big land-grab for service users, of course, and Microsoft does have a big war chest to fund it all.
Can the company dominate in the Cloud, where Google, Amazon, and so on are all major players too? You know, it's got a decent chance.
Let us know if the link does or doesn't work for you in various countries around the world!