This dsource project hosts candidate associative array implementations to replace D's aging, crufty implementation that interacts poorly with the current GC. Eventually there should be a benchmark suite.
SVN write access should be open to anyone with a dsource account, to make it simple to post your AA implementation for comment, etc. Implementations should be released under the Boost license or a similar license that is open-source, non-copyleft and does not require attribution in binary-only distributions.
[ArrayIndex] : Interesting implementation of KeyIndex and KeyValueIndex with compact array for data.
PyDict and RandAA hash tables [PyDict]
Dictionary implementation adapted from C python, experimental random hash table index sequence.
Built-in array implemented as a template module [HashTree]
Getting the Builtin Associative Array out of D runtime.
HashTree, pydict compared to builtin AA benchmarks [HashTreeBenchmark]
D Runtime replacement for aaA.d available D-Runtime replacement
Tango based HashMap, RandAA, Builtin, Hashtree, PyDict compared.