Baby wipes are probably the second most useful thing for horse riders following closely behind bailer twine. I always have a pack of unscented baby wipes in my lorry and use them for a whole variety of uses including but by far not limited to:
Last minute tack clean
Last minute boot clean
Cleaning hands after doing studs etc
Cleaning horses eyes/nostrils
Removing stable stain
If at a stay away show without access to a shower they can be used for a basic clean!