ecommerce hosting services

[Rob Becker]

Can anyone recommend web hosting services that provide ecommerce tools? 
If possible, I would like to find one that uses open source technologies
and allows for shell access and such niceties as php, mysql, etc.  I am
also open to using a provider that can offer open source web space and
tools and then installing a php based ecommerce package if such a beast
exists.  I am just getting started on this quest, so I would love any
feedback anyone has to offer.
Thanks everyone.
Rob