Yes. Coffee grounds are excellent sources of nitrogen. They also keep snails and slugs away, two pesky pests that eat and destroy orchids. Always use grounds from brewed coffee because they have a near neutral pH that is plant health-boosting.
Eggshells are just as beneficial and provide orchids with calcium, which fosters blooming. Put eggshells in a container and add water. Let the mixture steep for a few weeks. Mix a cup of the eggshell mixture and 1 gallon of water and water your orchids as normal.