At the 2012 meeting I broke my foot peg & needed to drill out the bracket, & a kind fellow racer lent me his drill & bits, it saved the day & of course, I took it straight back. A few other members of our team (the UK bike boys) ended up borrowing stuff too, and "Grateful" doesn't describe how we felt. We also lent stuff out. A French team urgently needed some metric bolts & in my spares kit, I had loads. You'd have thought I'd given him solid gold ones, he was like a dog with two tails.
Like Slim said, borrow & give. The other day I fixed a broken gear change on a Buell that had ground to a halt just outside my workshop. He started to reach into his pocket to pay me. I told him not to be daft, but if he sees a bike on the side of the road, to ask if he can help.