Phil Wheeler -wrote:

A visa? Won't a passport do it?

For many countries, no -- suprisingly many. Look here, for example:

http://travel.state.gov/travel/tips/...ures_1229.html

Visa requirements and fees are often on a tit-for-tat basis:
if they need a visa to visit your country, you're almost certainly
going to need a visa to visit theirs, and they're going to
charge you what you charge them.

The list of countries whose nationals can visit the USA
without a visa is *very* short.

Laura Halliday VE7LDH "Que les nuages soient notre
Grid: CN89mg pied a terre..."
ICBM: 49 16.05 N 122 56.92 W - Hospital/Shafte