The AGFL Grammar Work Lab - The formalism for the to attribute grammars related Affix Grammar over Finite Lattices developed at the University of Nijmegen is being applied to natural-language processing. Context-free grammars can be described on a primary context-free level augment - http://www.agfl.cs.ru.nl/
Micro Attribute Grammar System - The UU_AG system is a very simple program that reads a set of files containing an attribute grammar, in which semantic functions are described through Haskell expressions. - http://www.cs.uu.nl/groups/ST/Software/UU_AG/index.html
The lrc attribute grammar system - The system generates efficient incremental attribute evaluators and was written by one of the attribute-grammar formalizers. - http://www.cs.uu.nl/groups/ST/Software/LRC/
Ox Grammar System - An attribute-grammar compiling system based on yacc, lex, and C, the system embodies a yacc/lex/C preprocessor designed to bring attribute grammars to the mainstream of UNIX-based language development. It can also be used with Bison, Flex, and C++. - ftp://ftp.cs.iastate.edu/pub/ox/
The Fnc-2 Attribute Grammar System - An attribute grammar system based on strongly non-circular AGs that perform extensive space optimizations - http://www-rocq.inria.fr/oscar/www/fnc2/littlefnc2.html