Yes, a caching plugin would definitely help out there! Your site was featured in the last webdesigner depot newsletter (which has around 150K subsribers I think) and when I clicked the link I could not reach your site for 5 minutes...
Have you had a look at the W3 Total Cache plugin already? This drastically speeds up sites when configured correctly.
And sorry about the slowness, it's hosted on PHPFog but I think I need to tweak some WordPress caching options to speed it up.