I have looked at mine once, long time ago though. Now i have trillian and my logs are in C:/Program Files/Trillian.. try looking in Program Files for like an 'AIM' or maybe 'AOL' folder, might be in there.
Try your my documents folder.. thats where all my logs go, if not try the Aim foler that that the program is in.. could be in there..if not.. then im not sure lol and isnt there an option to change where they go?