You've done your microarray experiment (or your next-gen sequencing, proteomics, etc.) and you now have your list of candidate genes. What online gene-centric databases do you consult next to prioritize those candidates?
I'm interested in the big hitters in gene annotation like NCBI Entrez Gene, Ensembl, Uniprot, etc, as well as specialized databases that might be particular to your area (e.g., T1DBase for type 1 diabetes data, 4DXpress for expression data, OMA browser for orthology information, etc.)
I like very much Uniprot, it provides the best annotations for proteins: so, even if you are studying genes, I would have a look at that, to see the functions of the proteins coded.
For orthology, I use ensembl but I am aware that it is not the best resource for that. In fact, they predict orthology using only the longest CDS for each gene, so if you really care for orthology predictions you should look somewhere else.
And there is a wonderful tool called harvester, which allows you to obtain informations from many different databases at a time, for a certain gene: it cluster data from string, pubmed, kegg, etc...
Also, another gene-centric resource is GeneCards, which I think could be improved more but it is a sort of Uniprot for genes.