i've experienced foot-washing several times. never in a church service - it is quite meaningful when in a small group with people you feel close to. once was in a youth group, once in a small Bible study group, another time we washed one another's hands rather than feet. it really felt humbling and intimate - took a lot of trust - both being the washer and the washee. i think it would be sort of weird with strangers or people you don't know well.
We are often troubled, but not crushed;
sometimes in doubt, but never in despair;
there are many enemies, but we are never without a friend;
and though badly hurt at times, we are not destroyed.
- Paul, II Cor 4:8-9