GNU toolchain, which includes a great C/C++ compiler among many other things, is central to many free software projects. They are now accepting donations. I donated around 7 mBTC (milli-Bitcoin, as of 2017-09-11, 1 mBTC = ~ £5).
This was the first thing I've ever done with Bitcoin, and it was a bit of a faff. Buying bitcoin with GBP is not easy, and involves all manner of authentication steps, including mobile phone verification - so...much harder than getting, say, Euros or US Dollars.