The best font service I know is Google Webfonts, as the process of importing them into a Wikia very easy, you look for the fonts you want and click on the Use tab in the font board, you then get three choices to put the fonts into your site, afterwards you go to the Special:CSS page of your Wikia and copy-paste the following CSS code into the box and click save:
body, html { font-family: Font Name; }
Obviously replacing Font Name with the name of your chosen font.