A couple of times I've used a custom font as a game prop. In addition to notes and letters in foreign fantasy languages, I've made a magical notation font so I can "write" spells out to form a spellbook of sorts.
Now, to make things easy I generally use English to type my stuff out and then use the custom font to simply change letters out. For example, if I was making a Russian-language game prop I wouldn't necessarily actually use Russian (Cyrillic) but instead have Cyrillic letters mapped out on the English alphabet. In this case I'm going more for a look rather than readability in the original language. Then, depending on the PC's language skill (and mechanics) I can simply change back some/all of the text back to English.
There are already a lot of custom fantasy fonts on the interwebs that you can download and use. This free online tool for creating your own font (from http://www.myscriptfont.com/) is real easy to use, but you need a scanner. There are only a few steps:
- Download & print the template sheet
- Fill it out with a good pen
- Scan the filled out template
- Upload the scanned file
- Download & install your new font
Creating your own fonts can go a long way in making it possible to put a personal touch on a lot of gaming projects. On hand-drawn maps, for example, you can dispense with having to label everything as you draw the map and instead scan it in and then use your font to type out the labels. Since you can manipulate the text, it is a lot easier than trying to incorporate it into the drawing.