Comic Sans is the font you can often see on JavaRanch pages. As I understand, it was chosen to communicate the idea that the place you just came across is anything but formal.

Here Vincent Connare tells how the font was created.

I started with the font drawing software Macromedia Fontographer, trying to make the capitals in a similar form as the lettering used in DC, Marvel and all other company's comic books. The Dark Knight Returns a Batman book was one of the books I referenced often. I took care not to copy the letters but looked at varying shapes in different styles. Also most samples only used capital letters so I had little reference for them. I printed it out so that the weight was about the weight of the Marvel and DC books. I looked at the varying letterforms that each book had since all the letters vary because they are manually written.

If you are interested in fonts which are used in comics, here are more.

On a bit tangential note, here is an interesting article about fonts that "are recommended and used by dyslexic people", which says: "some dyslexic people find that Comic Sans is one of the more readable of the commonly-available Windows fonts".

And speaking about letter-induced diseases...

COMMON TYPOGRAPHIC DISEASES Various forms of dysfunction appear among populations exposed to typography for long periods of time. Listed here are a number of frequently observed afflictions.

TYPOPHILIA An excessive attachment to and fascination with the shape of letters, often to the exclusion of other interests and object choices. Typophiliacs usually die penniless and alone.

TYPOPHOBIA The irrational dislike of letterforms, often marked by a preference of icons, dingbats, and -- in fatal cases -- bullets and daggers. The fears of the typophobe can often be quieted (but not cured) by steady doses of Helvetica and Times Roman.

TYPOCHONDRIA A persistent anxiety that one has selected the wrong typeface. This condition is often paired with OKD (optical kerning disorder), the need to constantly adjust and readjust the spaces between letters.

TYPOTERMIA The promiscuous refusal to make a lifelong commitment to a single typeface -- or even to five or six, as some doctors recommend. The typohermiac is constantly tempted to test drive "hot" new fonts, often without a proper license.

Ellen Lupton. Thinking with Type.