I think that all the major parties in the USA can be considered as economically liberal. There aren't really any socialists or communists. In Belgium, France, Italy or Spain, for instance, the clivage between the left (anti-liberal, anti-globalisation, socialist, communist) and right (liberal, reformist or conservative) is very clear.
Conservatives are usually (not always) economically liberal, but socially conservative. In Belgium that is the Christian Democratic party. In the UK, it is the Conservative Party. In the USA it is especially the neo-cons of Bush. Conservative are almost always religious and close to traditions. True liberals (both economically and socially) are reformists (toward more freedom) both for the economy and social issues.
Socialists are usually economically anti-liberal, but can be quite liberal on social issues. Communists are usually anti-liberal on all the line. As for the Extreme Right, they can be anything. For example, France's Front National (Le Pen) is quite anti-liberal both economically (anti-EU, anti-globalisation) and socially (value traditions), but can also be quite liberal on some points. The Belgian Vlaams Belang is quite liberal on all the line, especially economically. The Nazi, like the Communists, were the paradigm of anti-liberalism (everything had to be controlled by the state, complete restriction of economic and social freedoms).
So, in my eyes, the modern Communists (e.g. in France or Italy) are the closest to the Nazi, followed by the Socialists and Conservatives (after all Nazi stand for "National Socialist", taking the anti-liberal stance of each party). The only true opposite to Nazism are the Liberals. The extreme version of liberalism are the Libertarians - but I don't think that extremes are good, even in the right direction.
Here are a few examples of true Liberals (whatever their party name or image is) :
- Britain's Liberal Democratic Party (+ Tony Blair and Gordon Brown, who are Labour just in name)
- Belgium's MR, VLD, and (despite its anti-immigration stance) Vlaams Belang.
- The Democrats in the US (maybe not all of them, but at least people like Clinton, Gore, Kerry, Kennedy).
- France's Francois Bayrou or Nicolas Sarkozy (parties are too confused to identify one of them as liberal)