Software for Associations Discovery

Azmy SuperQuery, includes association rule finder.
IBM SPSS Modeler Suite, includes market basket analysis.
LPA Data Mining Toolkit supports the discovery of association rules within relational database.
Magnum Opus, flexible tool for finding associations in data, including statistical support for avoiding spurious discoveries.
Megaputer Polyanalyst Suite, includes market basket analysis engine
SmartBundle, a market basket analysis tool for develop profitable retail product bundles and promotions. (30-day free trial)
Wizsoft WizRule: finds association rules and potential data errors; WizWhy uses association rules for data mining.
Xpertrule Miner 4.0
XAffinity(TM), for identifying affinities or patterns in transaction and click stream data

arules, a free R extension package which provides the infrastructure for representing, manipulating and analyzing transaction data association rules.
Apriori, a program to find association rules with the apriori algorithm (Agrawal et al.). Fast implementation that uses prefix trees.
Apriori, FP-growth, Eclat and DIC implementations by Bart Goethals.
ARtool, collection of algorithms and tools for the mining of association rules in binary databases. Distributed under the GNU General Public License.
DM-II system, includes CBA for classification based on associations, and many more features.
FIMI, Frequent Itemset Mining Implementations repository, including software and datasets.
Magnum Opus Demo, highly-functional demo software for finding associations in data, including statistical support for avoiding spurious discoveries.
opusminer, an R package providing an interface to the OPUS Miner algorithm (implemented in C++) for finding the key associations in transaction data efficiently, in the form of self-sufficient itemsets, using either leverage or lift.