Some of my favorites:
* An article on runes, including a runic alphabet. (Dethek?) As a bonus, had some runic riddles which were campaign seeds in their own right. ("I guard beneath / Rubies three, sapphires three / And crown of gold." - Who doesn't want to find that location?)
* "Be aware, take care: principles of adventuring success" - or something like that. Advice to the players about how to keep their PCs alive. Somewhat dated now, in that D&D has evolved beyond its DM-vs-players paradigm. But a new series for the players (rather than endless templates and upgrades for monsters = the DM) would be welcome.
* The aforementioned story about the girl playing what we would now call a Multi-User Dungeon (MUD) or MMORPG was outstanding. I still have the battered, dogeared copy of that magazine somewhere. (It has an illustration of a black dragon being soothed by a bard on the cover.)
* An article describing the six ability scores. Was very good on differentiating Intelligence from Wisdom and Strength from Constitution. An update for the modern era would be especially helpful to new players.
* "Of rogue-stones and gem-jumping", one of Ed Greenwood's Realms articles. Some of this material made its way into the FRCS, but not the evocative backstories. (Again - campaign seeds!)