Chumras in bein adam l’chaveiro I’ve noticed (very partial list, in no particular order):
Giving tzedakah when not required al pi din.
Even when required al pi din to give, giving more than the minimum.
Filling up the washing cup for the next person in line.
Inviting needy Shabbos guests.
Giving chizuk to those in need.
Giving (requested/desired) advice to those in need.
Hatzolah.
Bikur Cholim (private, and organizations).
Free tutoring/help learning.
Store owners giving refunds when neither required nor good business policy.
Contractors doing a few small extras for no extra charge (not to gain more business).
Aveilim being mevater on the amud when not required.