Kitchen utensils: measuring devices, stirers, mixing bowls, and the like, are useful tools for a mage or alchemist to have handy in the workshop; connected to this is that some of the containers might be normal snack foods
A box of rocks: (this could be a whole thread on its own); some could be mana storage/generators, some valuable gems, some have historic or personal significance, and some will just be pretty
A mirror where you can almost make out something looking back at you
Various drawings & paintings: (taken from a pc in Midian) some will be magical symbols, half-finished ideas for new spells, and some will just have some artistic value, either figure studies, or just to look pretty (this pc was a necromancer who was quite skilled in art, some figure drawings were ideas for experiments with the Undead, some were just for their art value or just for practice)
A stack of old cartriges for a console video game (not included)
Taxidermy: either rare or interesting stuffed animal carcasses, some may have personal significance (e.g. the squirrel that almost killed the mage)
Incense, holders, & oil burners: with the stink from some experiments, the mage might want to make the place smell better, or just to aid in meditation & study
Books whose names on the spine can only be properly read (or even at all) via phosphorescence when the lights are low, or under other specific lighting conditions... where does a dark-ages wizard plug in his blacklight lamp?
Mouse skeleton: sitting on a shelf amidst other nicknaks; no significance, other than the mage is a lousy housekeeper
Circles: permanently inscribed, or just a dedicated section of the floor (or wall or ceiling) for casting summoning, protection, or travel/gate magic
Comfy chair: every mage's study needs somewhere comfortable to sit for long periods; this may be the only place to sit, or other chairs may have books stacked on them
Messy desk: with various papers, pens, & sundry other items seemingly randomly scattered about; this one is almost an essential central piece to any wizard's study/lab