Wow we really have quite the similar taste o.O ... I'm a sucker for yankee dramas, they are my favorites :)
How about "Misaki Number One!" ... it's similar to Gokusen, but in this one the teacher is not a yakuza member but the number one hostess in a host club and like in Gokusen the school can't know about it :P . The students are yankees, they even have their own class, like in Gokusen, but in this drama there are boys & girls together in one class.
There is also a drama called "Gachi Baka" ... I personally did not like it but maybe you do, who knows ;)
Then there is KO One ... it's a bit different from the usual yankee dramas as it has fantasy in it ... the delinqent students are together in the same class and there is lots of fighting, not fistfighting but weapon-fighting (for example a pan). There is also a teacher who tries very hard :D ... I really liked it and I marathoned it although I understand that this kind of drama is not everybody's cup of tea.