Part of the answer depends on what kind of image you're looking to produce.
If you just want a 500px wide image of a topo map, go to http://caltopo.com/map.html
(or one of several other similar sites) and take a screenshot, problem solved.
If you want something that prints well onto 8.5x11 paper, it gets a little more complicated. My site can do that, but it doesn't put neat tickmarks on the border or all the extra information on the bottom that Topo! does. Getting a clean full-page print also requires Google Chrome as browser printing is not nearly as evolved as printing from desktop apps. Either way, you're probably looking at printing to a PDF file, converting that PDF to a jpeg, and then opening it in an image editor like photoshop. When you're done, the jpeg file is probably going to be massive if it has enough resolution to print well.
The USGS site is great, but once you cross a 7.5' boundary you need to start stitching images together.