User needs for a given product type can be quite heterogeneous. Segmenting the market and providing solutions for average user needs in each segment is a partial answer that will typically leave many dissatisfied ? some seriously so. We hypothesize that providing users with ?toolkits for user innovation? to enable them to more easily design customized products for themselves will increase user satisfaction under these conditions. We test this hypothesis via an empirical study of Apache security software ? ?open source? software that is designed to be modifiable by skilled users. We find that heterogeneity of need is high, and that many Apache users are dissatisfied with standard security functionality on offer. We also find that users creating their own software modifications are significantly more satisfied than are non-innovating users. We conclude by suggesting that the ?toolkits for user innovation? approach to enhancing user satisfaction might be generally applicable to markets characterized by heterogeneous user needs.