I would like to figure out if any of the solar system planets have ever eclipsed a particular star (i.e. crossed the line of sight from Earth to the star) or will eclipse it in the future. Is that possible to do, given that I know the RA and Dec of the star I'm interested in? Is there any astronomical software that would allow me to do that?
(Greg Miller and Heopps have already provided links for tables of occultations.) Off the top of my head I am familiar with Uranus's occultation of the star SAO 158687 (also known as HD 128598) on 10 March 1977 that led to the discovery of the Uranian ring system. A team from Cornell University observing the event from NASA's Kuiper Airborne Observatory (now defunct) found that the star dimmed five times before slipping behind the planet and then again five times after emerging from behind the planet. The team eventually concluded that a system of nine rings around Uranus would account for its observations.
In 1986, Voyager 2 imaged these nine rings and detected two more. In 2003-2005, the Hubble Space Telescope found another two rings, bringing the current known total to thirteen.
Edit (added 22 Nov 2022): The Neptunian ring system was discovered by similar means - stellar occultations by Neptune. The Neptunian rings are sometimes described as clumpy or clustered or "ring arcs." Voyager 2 confirmed the existence of Neptune's rings.