I think a 500/pack unruled white index cards is ideal for just about anything: writing reminders organization especially during a presentation and above all all kinds of schooling. You don't need lines for the above. And if the price is right go for it! These are my best kept inexpensive secret!
My hobby is entering sweepstakes via internet and US mail. Mail in entries require name address and occassionally other info hand printed on an unruled 3x5 card. I consistantly purchase the Staples 500 pack of 3x5 unruled cards. They provide the correct size durability to withstand mailing and are always clean white and easy to read. I have won many prizes using these cards and find them to be better quality than other well know brands .
The index cards were for a business project I was working on! They served their purpose and I could not beat the price for the amount that came in a package.