It is desirable to reduce the amount of data collected in sensor networks to reduce energy consumption and to extend network lifetime while one should extract as much information as possible to allow support for heterogeneous user queries. There have been a number of aggregation proposals, aiming at reducing the amount of data communications within the sensor network, mainly focused on supporting limited and simple types of queries such as SUM, COUNT, AVG, MIN/MAX. Unfortunately, user queries are not limited by these simple types of aggregates and cannot be predicted a-priori. In this paper we propose an aggregation-framework that produces regional digests at a parameter defined granularity such that arbitrary user queries can be supported. Since the success of the aggregation policy greatly depends on the integrated routing mechanisms we evaluate the performance of our approach under alternative routing approaches. Our experimental results suggest at least 3-fold improvement in spatial accuracy at a relatively small expense of increased energy consumption