I have only just noticed that J. Donald Monk has made his admirable Mathematical Logic (Springer, 1976) freely available for download, which could well be of interest to some readers here.
A smaller number of discerning readers might also be interested his book-length Lectures on Set Theory (work in progress, it seems, last updated a few months ago). Unlike that earlier more discursive book, these are rather terser notes. But they consequently cover a great deal, including — on a quick look — a significant amount of relatively recent material. The main parts of the Lectures are
- Elementary Set Theory
- Generic sets and forcing, I
- Infinite combinatorics
- Generic sets and forcing, II
- Continuum cardinals
This seems as if it could be a useful resource.