I have organic, not-homogenized milk which is just starting to get a little bit sour. How can I make use of this?

Get rid of it. It is probably developing some really bad bacteria if it is organic and not pasteurized.

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You say it is not homogenised, you don't actually state if it is pasteurised or not.

If it is pasteurised then bin it, as the only bacteria present will be bad ones.

However if it is actually raw milk the good bacteria multiply and keep most of the bad in check. I always use raw milk and if mine is starting to sour I use it to make yoghurt.

Other ideas here:

Don't Cry Over Sour Milk (Using Your Raw Milk Gone “Bad”) | Keeper of the Home