What's the best source for information about specific genes?

We are interested in studying gene expressions in living animals, by means of different in-vivo and in-vitro imaging techniques. We also plan to execute tests on living organisms by using Affymetrix or Navigenics or equivalent DNA microarray test chips, but we know that interpretation of such tests are closely related to the ability to execute reliable and effective reannotation vs. existing validated databases of identified genes. We know that services provided by Affymetrix often provide little informative annotation for most known genes (identified as "transcribed locus"), and we would like to know if anyone in the world can provide an effective reannotation service using our DNA microarray test files, i.e. by executing rigorous tests of our Affymetrix chip probeset sequences against all currently available transcript sequences in latest database releases.

This is a question about gene annotation. I think it's really about how to attach a small bit of truly useful information to many genes in a list. The specific question seems to concern Affymetrix data files in particular.

A list of standard sources for information about human genes follows (in most cases I provide a sample link to the page for CFTR). Entries in these databases are extensively linked to each other.

OMIM, Online Mendelian Inheritance in Man. (CFTR)
Entrez Gene, NCBI's searchable database of genes from RefSeq genomes. (CFTR)
GeneCards, a searchable, integrated database of human genes.(CFTR)
HGNC, HUGO gene nomenclature committee, (CFTR)
Ensembl, genome databases for vertebrates and other eukaryotic species. (CFTR)
Ensembl's BioMart tool may be one answer to this question).
GeneWiki, Wikipedia's gene pages. (CFTR; HBB)