Probably garbage but those wizards at HDretrovision have been thinking of making a RGBS/Component/S-video/Composhit/Liquid Snake RF to HDMI adapter scaler for a while now codenamed the HDMIzer. Their findings is that a lot HDTV's can support some crazy resolutions over HDMI due to it being included in the standards (if the manufacturer included it which they usually do as they copy pasta), including our good friend 240p. Even better yet is doing a simple line doubler for a clean 480p image and letting your tv's scaler work its arcane magic.
I have a couple of those. They aren't fantastic but they do the job for the price. Once you get the settings right, they work just well enough. I have an MVS board running to a 32 inch tv. Ive also seen them paired with vga to hdmi converters and work decently.