From the publisher's website:
These stand-up, miniature table tents help parties to keep track of the spells that are up, and what bonuses that they give to the players. This set contains many of the more useful group buffs, i.e. Hero's Feast, Prayer, Paladin's Aura of Courage, and nine more of D&D 3.5's most useful group spells/abilities.
We designed this set after repeatedly having people miss attacks or saves because they forgot about bonuses that they had. It makes it a lot easier to have a stand that shows that you are immune to poison because someone cast Hero's Feast at the beginning of the day.