Dave

Hurley & Libby / Libby & Locke Via SRMHI

In Dave, we find out Libby was  at SRMHI as a patient at the same time Hurley was a patient there.  In Fire + Water while doing laundry in the hatch,. Hurley asks Libby,  "Do I know you from somewhere?" As of the end of season two Hurley still  hasn't recalled this memory nor if Libby realized that the two were at SRMHI together.  Now we may never know.

 

This also makes a slight connection with Locke whose mother, Emily, was also a patient at SRMHI as revealed in Deus ex Machina.