Intermediate level set theory texts: [1], [2], [4], [8], [10], [12].
More advanced than these, but possibly within your present reach are [6] and [11].
Descriptive set theory can be found in some of these (e.g. [6] and [12]), and more fully in [9] and [14].
A lot of useful material on cardinal and ordinal numbers is in [5] and [13].
[3] is a good elementary reference for topics that are often omitted in standard elementary texts (e.g. arithmetic operations on linear orderings) and for historical/bibliographical information.
Finally, Handbook of Set Theory [see also here] might have some useful articles, but at this point I have not had a chance to look at it very carefully.
[1] Krzysztof [Chris] Ciesielski, Set Theory for the Working Mathematician, London Mathematical Society Student Texts #39, Cambridge University Press, 1997, xi + 236 pages. table of contents
[2] Frank Robert Drake and Dasharath Singh, Intermediate Set Theory, John Wiley and Sons, 1996, x + 234 pages. table of contents book review
[3] Abraham Adolf [Adolph] Halevi Fraenkel, Abstract Set Theory, 3rd revised edition, Studies in Logic and the Foundations of Mathematics, 1966, viii + 297 pages. review of 1953 edition
[4] András Hajnal and Peter Hamburger, Set Theory, London Mathematical Society Student Texts #48, Cambridge University Press, 1999, viii + 316 pages.
[5] Michael Holz, Karsten Steffens, and Edmund [Edi] Weitz, Introduction to Cardinal Arithmetic, Birkhäuser Advanced Texts, Birkhäuser Verlag, 1999, viii + 304 pages. book review
[6] Thomas J. Jech, Set Theory, Springer Monographs in Mathematics, Springer-Verlag, 2003, xiv + 769 pages. 2006 edition 2011 edition
[7] Winfried Just and Martin Weese, Discovering Modern Set Theory. I. The Basics, Graduate Studies in Mathematics #8, American Mathematical Society, 1996, xviii + 210 pages. list of topics
[8] Winfried Just and Martin Weese, Discovering Modern Set Theory. II. Set-Theoretic Tools for Every Mathematician, Graduate Studies in Mathematics #18, American Mathematical Society, 1997, xiv + 224 pages. list of topics
[9] Alexander Sotirios Kechris, Classical Descriptive Set Theory, Graduate Texts in Mathematics #156, Springer-Verlag, 1995, xviii + 402 pages. corrections and updates (4 October 2013)
[10] Péter Komjáth and Vilmos Totik, Problems and Theorems in Classical Set Theory, Problem Books in Mathematics, Springer, 2006, xii + 514 pages. table of contents book review
[11] Herbert Kenneth Kunen, Set Theory. An Introduction to Independence Proofs, Studies in Logic and the Foundations of Mathematics #102, North-Holland, 1980, xvi + 313 pages. 2011 edition review of 1983 edition
[12] Azriel Levy, Basic Set Theory, Perspectives in Mathematical Logic, Springer-Verlag, 1979, xiv + 391 pages. Reprinted by Dover Publications in 2002. review
[13] Waclaw Franciszek Sierpinski, Cardinal and Ordinal Numbers, 2nd edition revised, Monografie Matematyczne #34, PWN--Polish Scientific Publishers, 1965, 491 pages. review of 1958 edition
[14] Sashi Mohan Srivastava, A Course on Borel Sets, Graduate Texts in Mathematics #180, Springer-Verlag, 1998, xvi + 261 pages.