i as well abused ritalin for a long time. up until yesterday when i ran out .. :-( ..... trust me, ritalin abuse is no fun. back when i was doing it really heavily, i lost a lot of weight, started smoking a pack a day, had to deal with sweating and palpitations and a complete inability to do anything marginally useful without being on at least 60mg... i have done up to 240 mg. of ritalin in a day. it all started as a coping device to deal with the pressures of school... i never did my work anyway, and then convinced a doctor i had "add" (although if there really is such a condition, then i most definitely do have it). i thought i was getting this endless supply of uppityness and productivity, little did i know that after 5 days of using it, i suddenly needed it just to be able to match my previous mediocre performance in school. very addictive stuff.
so yeah don't do it!