Genome Project Focusing on gene ADRB2?
If you are looking for variations in a gene, there are a few databases you an consult. 

You can of course use the usual genome browsers, search for your gene and then select the variations listed. For ADRB2 this looks like this on Ensembl. If you plan to retrieve and compare data from different genomes/genes, I really recommend learning how to use Biomart, as this is a very powerful tool.

Then you can use specific databases or search engines, which only target SNP's. Examples would be: DBSnp and SPSmart (which queries different databases).