Funny questions but;

You drill a hole through a little round thing and get a bead, you drill a hole through a conker and get a ..conker, are there any other similar round things with holes in?

your head

holes in wheels to attach them to cars

Buttholes.

Beads can also come from buttholes

ferrite cores for interference suppression
current or toroidal transformers
weights for fishing lines
those big blocks on ropes around nets and stuff on fishing boats

the mint with the hole POLO

Washers, for nuts and bolts are blanks without the holes
Some coins have holes in the middle too.

I was more thinking spherical things... people start drilling holes in things and then I gotta explain why  

dogs balls ?

(the rubber kind)

they make tough rubber ones with a hole through the center... that way its still tough and will last a while... but it will still squash when smaller dogs bite them

plus there a bit lighter than the solid ones... so there better if your throwing them for the dog to catch

And the point to this post is .....

I am curious as to why you would like to know ... been smoking some doobies have we!