GM's Aid II: Condition Cards is the second product in the GM's Aid line from Purple Duck Games. The cards have been designed as a game aid for players and gamemasters alike. They have been formatted to print on any standard-size business card paper, or you can just print them on cardstock and cut them out using the lines as guides.
If you are a player, print the cards and keep them handy, and whenever your character is struck blind by a spell, knocked prone by a powerful blow, or simply invisible thanks to a handy potion, you can pull out the requisite card and - voila! - you have all the information you need to handle any adjustments to die rolls, combat stats, skill checks, etc. When your condition ends, simply return the card to the stack.
If you are a gamemaster, you might even consider printing out two or three sets of these cards, as multiple characters can sometimes be affected by the same condition. That way you can label the cards in pencil or color-code them with reusable sticky tags, or hand them to the affected players for the duration of their condition.