Sometimes I've noted my Russian-speaking friends use "говорил" where I'd think you'd say "сказал." Is that common informal usage?
Besides that, I've noticed them write 3rd person sg. forms with a soft sign, example:
Я сегодня ходила в театр, тебе нравиться театр?
BTW, what's with the ходила there? Shouldn't it be пошла? I've seen Russians use the indeterminate forms of the verbs of motion much different than the way they were explained in my books... If it's indeterminate motion, how is it possible to have a determined destination for such motion? Sometimes I think it looks more like you use "indeterminate" form for habitual action("I go to St. Petersburg every winter"), imperfective determinate for continuing action("I'm going(right now) to St. Petersburg), and perfective for perfective.