Just an SSR. I use a 10A SSR to control a 2A load and it has no heat issues, but depending on how much power you're going to push through it you might need a heatsink on it or some sort of cooling. Just hook the RCA jack to the input of the SSR, run one 110V wire directly to the plug and the other through the SSD.
I used a double outlet and cut the strip between them on the switched side so I could have one always-on jack and one switched. Instead of a C14 receptacle I just cut the end off the power cord and wired it in directly. Don't be crazy and use 20A parts, standard service is 15A and that's plenty and makes it a bit easier to work with the wire.
Im finally getting around to this. Will this SSR work?
http://www.amazon.com/exec/obidos/ASIN/B004HZN628/tvwb-20
And are people using pumps to circulate water? I was thinkin about using this: http://www.amazon.com/exec/obidos/ASIN/B007XHZ25G/tvwb-20. Can I hook this up to the SSR as well?