The Palantíri:

Unbreakable crystal spheres crafted by the Noldor in Aman. They could be used for seeing what happened at a distance, or with two or more, they could be used to communicate. There were eight, of which seven were given to the Lords of Anadûnê as a gift. The eighth, the Master Stone was kept in Tol Eressëa. These seven escaped the Downfall in the ships of Elendil and his sons. Four of the seven were kept in Gondor and the other three in Arnor. They were kept in the following locations:

These were the seven stones of the verse (LOTR.620):

Tall Ships and tall Kings
Three times three,
What brought they from the foundered Land
Over the flowing sea?
Seven stars and seven stones
And one white tree.

By the end of the Third Age, only four of the palantíri still survived: the ones at Orthanc, Minas Morgul, Minas Tirith and the Tower Hills. The palantir of Minas Ithil was destroyed in the destruction of Mordor, The palantir of the Tower Hills was likely taken over the Sea in the Last Riding of the Keepers of the Rings. The palantir of Minas Tirith became so ingrained with the image of Denethor's death that it was pretty much unusable and the last, the palantir of Orthanc, the Kings of the Reunited Kingdom kept.

The Phial of Galadriel:

A magical phial containing the light of Eärendil, the Evening Star. This was a gift to Frodo:
"And you, Ring-bearer," she said, turning to Frodo. "I come to you last who are not last in my thoughts. For you I have prepared this." She held up a small crystal phial" it glittered as she moved it and rays of white light sprang from her hand. "In this phial," she said, "is caught the light of Eärendil's star, set amid the waters of my fountain. It will shine still brighter when night is about you. May it be a light to you in dark places, when all other lights go out." (LOTR.397)

It was instrumental in Frodo and Sam's escape from Shelob in the pass of Cirith Ungol.

The Hobbit
The Lord of the Rings
The Silmarillion
The Complete Guide to Middle-Earth by Robert Foster
The Unfinished Tales