I've started using s3-bash in a few of my ec2 scripts. It took me a little while to work out the exact syntax so I thought I'd share:

> Get bucket listing:

s3-get -k {accesskey} -s /{path}/{secretid} /{bucketname}

> Get file from bucket:

s3-get -k {accesskey} -s /{path}/{secretid} /{bucketname}/{filename} > {filename}

> Upload file to bucket:

s3-put -k {accesskey} -s /{path}/{secretid} -T /{path}/{filename} /{bucketname}/{filename}

> Delete from bucket:

s3-delete -k {accesskey} -s /{path}/{secretid} /{bucketname}/{filename}

Legend:
{accesskey} = AWS Access Key Id
{secretid} = AWS Secret Access Key Id File
{bucketname} = testjosh
{filename} = index.cfm
{path} = folder