?? (Chi Rho) are the Greek letters that form the Labarum, or the first two letters of "Christ" in Greek
Athlon XP, a line of central processing units by AMD
Cross-platform ("X" looks like a saltire cross and is often used to replace this word or its synonyms in abbreviations)
An emoticon expressing disgust, general discontentedness, or 'being dead'. The X represents wincing or crossed out eyes, while the P represents a mouth with a tongue sticking out.
Experience points, in a role-playing game, representation of a character's advancement and improvement in skills