Note: I’m not claiming that these are all correct, but there are some groups who consider these kulos to be part of their mesorah.
1) Eruv in cities with fewer than 600,000
2) Chodosh – the Bach’s heter
3) Sukkah on Shmini Atzeres
4) Peah nochris
5) Small shiurim (cf. Chazon Ish’ shiurim)