The development of highly accurate Named Entity Recognition (NER) systems can be beneficial to a wide range of Human Language Technology applications. In this paper we introduce three heuristics that exploit a variety of knowledge sources (the World Wide Web, Wikipedia and WordNet) and are capable of improving further a state-of-the-art multilingual and domain independent NER system. Moreover we describe our investigations on entity recognition in simulated speech-to-text output. Our web-based heuristics attained a slight improvement over the best results published on a standard NER task, and proved to be particularly effective in the speech-to-text scenario.