Do read Matt Yglesias’s interesting post (and here), but supply-side thinking simply isn’t that influential anymore. To show this, the entry on supply-side economics from Conservapedia is neither fleshed out nor current. Conservapedia is not a reliable source but it is a information aggregator of sorts for what is an influential idea on the right.
Here is their painful (but also obsolete and undernourished) entry on the Laffer Curve. This claim boggles the mind: "In the Reagan era, the Laffer Curve demonstrated that tax cuts lead to a near doubling of federal tax reciepts ($500 billion to $900 billion)." Might Reagan’s huge tax increase have had something to do with that?
I know one can find cites to supply-side economics by Giuliani, McCain and others, but the "starve the beast" theory — rightly or wrongly — is far more popular with the Right these days. Many people will use Laffer Curve claims to hide their real agendas but that is distinct from the Laffer Curve having much influence.
p.s. I do recognize that these Conservapedia entries may change very soon but they were underdeveloped when I went to visit them.
Addendum: Here is the former Jane Galt on said topic.