This great site just saved me a couple of hours of work.
What does it do? Yes, it creates favicons for your website, but not just one favicon.ico file, it creates a complete set of 27 favicons in all needed sizes and types to satisfy any browser, from Internet Explorer to the iPhone 6.
I stumbled upon this site while I was looking for a way to finally prevent these annoying “404” entries in the server log that are caused by browsers requesting particular, non-existent favicon files from your site, especially apple-touch-icon and apple-touch-icon-precomposed.
It’s interesting that I found lots of creative tips on how to work around this annoyance but actually few people seems to have plans to do the most obvious: creating the missing icon files.
This site works as simply as can be: you upload your graphics file (min. 260 × 260), choose some settings and 3 seconds later you can download the complete icon set, including all necessary meta files as well as the link entries for your header.php. You can even customize how your icons will appear on mobile devices!
One tip: Don’t miss the tab with the compression setting. It defaults to no compression but you really should enable at least the first compression level. This will save you about 60% on icon file size, at no visible quality loss.