After that, you could dig deeper with Andrew Appel's _Modern Compiler Techniques in {ML,C}_ books. The ML one is better, IMHO. Those cover other methods (LL, LALR, SLR, etc.) in greater detail, and I'd also recommend either for learning compilers in a heartbeat. (Appel's _Compiling with Continuations_ is also excellent, but doesn't cover parsing.)
Following that, Dick Grune's _Parsing Techniques: A Practical Guide_ (http://www.few.vu.nl/~dick/PTAPG.html) is a good reference...and thorough. If you're reading it to learn the basics, it might seem a bit dry, but I think it's at a sweet spot between depth of coverage and deference to the extensive bibliography. I have the second edition; the first is free online. Not sure about the differences, but the coverage of fundamentals probably haven't changed much. Also, while the other two are compiler books with chapters on parsing, this one is 100% parsing, and gets to a lot of interesting parsing algorithms (e.g. Earley parsing) that don't usually get much love in compiler texts.
Some people will also recommend the Dragon book, but I think those three will be more helpful. I haven't read the new edition, but the old seems drier & less thorough than the Grune book, less direct than the Wirth book, and less modern than the Appel book.
Also: For learning lex and yacc, the intros in the _4.4BSD Programmer's Supplementary Documents_ ("PSD", included with OpenBSD and probably the other BSDs, and not hard to find online) are hard to beat. The O'Reilly _Lex and Yacc_ book somehow manages to be roughly ten times as long yet less informative.
And if you have full control over the syntax used, S-expressions (Lisp), RPN (Forth), or Lua/JSON will let you dodge the issue of parsing entirely.