может и глагол ИЛИ может быть и глагол

[upthera44.livejournal.com]

 I've never been able to figure out how the following two constructions are used. When you want to say something like "We might (do something)" or "Maybe we'll (do something)" -- sometimes people use может and something может быть

For example: 

Может быть поженимся.

Может поженимся.

When are может and может быть used and what's the difference?