Modify your site to make use of multiple stylesheets with CSS3 media queries, which (the author claims) can get your site mobile-fiendly in an evening.
Make Your Website Mobile Friendly in One Night – David Cole
For creating our mobile site, we’re going to be primarily harnessing the power of the max-width property. Basically we’re going to tell our website to use different stylesheets depending on the width of the device’s screen. What’s great about this is that the mobile platform (iOS, Android, Windows Mobile) doesn’t matter, since the adjustments are made with screen size only!