The Go'auld tablet is the Goa'uld version of a journal. One page appears immediately, and others need to be read by using the small oblong page turning device with the stone tablet.
The object is in two parts. One is a flat triangular shaped mineral with Goa'uld language appearing to be engraved on it. The second part is a page turning device, which is an ovoid stone that passes over the tablet and changes the writing appearing on the "tablet." Instructions and information on Goa'uld experiments and technology are often stored on the devices. Anyone can operate the tablet and page turner, not just individuals with the naquadah signature.
SG-1 first encountered a Goa'uld page turning device on Argos (1.09 "Brief Candle"). Daniel Jackson discovered a hidden panel under the statue of Pelops that held a tablet and page turning device inside. The writing was an obscure Goa'uld dialect, and he and Teal'c worked together to translate it, discovering records of Pelops experiments with a "virus" (later discovered to be nanites) on the people of Argos, making them age artificially.
Another tablet was discovered in the final meeting place of the Linvris (3.04 "Legacy"). On it were the beginnings of a battle plan the Linvris were going to use to take on the system lords. However the page turning device had been replaced by a fake one. The Goa'uld fighter Ma'chello had copied the form of the device. It did not work to turn the pages, but when used against a tablet, it released ten tiny organisms that infected the user–killing Goa'uld symbiotes, but making unblended people appear schizophrenic. This later symptom was discovered when Daniel Jackson tried to use the device, and unwittingly got himself infected with the last remaining organism.
When SG-1 discovered Nirrti's hidden lab on Hanka (P8X-987), they found a Goa'uld tablet (5.06 "Rite of Passage"). Daniel was able to read the tablet and learn how Nirrti was using the lab to do experiments on the Hankan children, including Cassandra, in the hopes of creating a Hok'tar, an advanced human host.
–Aurora 14:11, 22 November 2008 (PST)