lightJacc is a small but strong grammar parser generator. It adopts a parsing strategy of its own: dynamic concurrent parsing -- which made it much stronger than LR or LL family CCs (YACC, ANTLR, etc), but still keep good performance.
Complete LALR(1) parser generator and engine in PHP.
Complete LALR(1) parser generator and engine (like BISON or YACC) but it's all done in PHP, and the input grammar is easier and more maintainable. Write your actions in PHP. Generate PHP output code. Drive your parser with PHP. Wanna make a language?
Many Tools: PHP-based context-free grammar (CFG) parser generator, simple scanner generator, and nascent object relational mapping/query language in PHP. Talks to Postgres, MySQL for now. Needs PHP5. Comes with (relies on) many convenience functions.