Recently added to the courseware page :
A nice course in modal logic (syntax, semantics, completness, logic of provability, logic of tense, intuitionist logic) : F. Veltman and Dick de Jongh : Intensional Logics (.pdf, 109p.)
Lambek's classic :JoachimLambek:The mathematics of sentence structure (1958)
And a general introduction to algebra somewhat logically-oriented, with chapters on lattices, on application to model theory etc. : Stanley N. Burris et H.P. Sankappanavar : A course in universal algebra (.pdf, 331p, millenium edition)