Well this might surprise people but yes! You can indeed. Using affiliate marketing sites you could not only make a few pounds, but also help friends decide about all sorts of things! From will writing to gift choosing, you really can earn money and add real value to your friends stream.
The top affiliate marketing sites are Amazon Associates Program (https://affiliate-program.amazon.co.uk) which is great for helping friends out that just happen to live in the same county as you, and the eBay Affiliate Program (https://www.ebaypartnernetwork.com) which is best if you have more international friends than local ones. Both are great examples of simple to use networks that can turn just about anyone into an affiliate marketer. But there are many more out there.