It provides lots of computable invariants in contact geometry, in particular the contact invariant defined by Ozsvåth and Szabó via open books and the Giroux correspondence. For example, on Seifert fibered spaces the question of whether tight contact structures exist was completely solved by Lisca and Stipsicz, and the classification was completed in many of these cases in several other papers; and Ghiggini used it to exhibit contact structures which are strongly fillable but not Stein fillable.

Similarly, the LOSS invariant (named after Lisca-Ozsváth-Stipsicz-Szabó) and the related, easily computable Ozsváth-Szabó-Thurston grid diagram invariants of Legendrian and transverse knots were used by Ng-Ozsváth-Thurston to successfully distinguish many pairs of knots in the standard contact $S^3$, and been used to prove other properties such as the fact due to Etnyre and Vela-Vick that the complement of the binding of any open book of any contact structure has no Giroux torsion. (According to recent work of Baldwin--Vela-Vick--Vértesi, these invariants are the same for knots in the standard $S^3$.)