There are multiple, though not particular common, references to Earth and its surrounds in Star Wars EU material.
Probably the best-known is the cancelled, and therefore non-canon novel, Alien Exodus, which would have used both space and time travel to link George Lucas' previous films, American Graffiti and THX 1138, set on Earth, to the Star Wars films. This project never went ahead, but would have changed a lot of subsequent EU material, such as making Corellia the homeworld of humanity in the Star Wars galaxy, rather than Coruscant as was eventually (probably) established as the case.
The second best-known example is the previously-mentioned Into the Great Unknown. This would have had Indiana Jones finding the Millenium Falcon, crash-landed here on Earth. This was published, but considered non-canon.
Christmas in the Stars implies that Christmas is celebrated in the Galaxy Far Far Away, which implies contact with Earth.
The single best example from the EU, one with a decent degree of canonicity, is Monsters and Aliens from George Lucas. While Leland Chee has stated that it is non-canon, there are several sources mentioned in the book which are treated as canon, notably the gossip columnist Dyslogia Twang, who mentions Earth in a column.
By far the best example, however, is the fact that in The Phantom Menace, several members of the same species as the alien from E.T., the Extra Terrestrial are onscreen. Later EU material expanded on this.
EDIT: I've already had my answer accepted (that was quick) but I felt I should add a link to this question, which is related to this one. It lists several mentions of animals that originated on Earth being mentioned in Star Wars media, as does the first page I linked to above. This question and this question are also related. I do not feel this question is a duplicate of those questions though, so I won't vote to close this question on those grounds, and I would suggest that no-one else do so either.