Advertising one's publication

After posting a preprint on arXiv, or after an accepted paper appears online, how to bring other's attention to it?

(Unless one is already a big name in one's field, or one proves a long-standing and well-known open problem, I doubt that just waiting for things to happen is going to suffice.)

For sure one can give talks or present posters on relevant conferences. But are there any other methods of bringing it to the attention of others who might be interested and for whom it may be beneficial?

The question is both about "classical" methods and any relevant Internet tools.