Here is a brief record of a few actions during the marches for the 24hour general strike organized by GSEE-ADEDY (umbrella of workers unions) on the occasion of the discontent on the government economic politics. During the strike, most schools, banks, state services remained closes, while there where no flight of olympic airways, nor metro, tram, trolley and bus transportations.
In Athens: In the beginning of the march, demonstrators invaded a bank that remained open, and after they got the employees out, aused damages and set the bank on fire with a molotov. During the march, demonstrators sabotaged many of the machines that beep when merchandise are stolen from large stores, while a group expropriated books from Ianos central bookstore, and distributed many of them to the demo. MAT (riot police) brigade that tried to break the march were repelled by a bloc of dock-workers after they clashed face-to-face, but later on MAT cops were found inside the university "police no-go area", at Propilea, and attacked demonstrators with tear gas when they tried to kick them out. In front of the parliament, MAT police had blocked the way so when student blocks tried to pass through, there were some clashes.
Source (red antireporters): http://athens.indymedia.org/front.php3?lang=el&article_id=917534
In Volos, (http://athens.indymedia.org/front.php3?lang=el&article_id=917682), there is a report that bank CCTV cameras were broken during the march.
In Mytilini, during the marches surveillance cameras were spraypainter by demonstrators. (greek report by "proletarians withour illusions" at http://athens.indymedia.org/front.php3?lang=el&article_id=917254)