I

I didn't change anything!
I see no X here.
I for one welcome our new X overlords
IANAL
IBM
ICBM address
ice
ID10T error
idempotent
IDP
If you want X, you know where to find it.
ifdef out
IIRC
ill-behaved
IMHO
Imminent Death Of The Net Predicted!
in the extreme
incantation
include
include war
indent style
Indent-o-Meter
index of X
infant mortality
infinite
infinite loop
Infinite-Monkey Theorem
infinity
inflate
Infocom
initgame
insanely great
installfest
INTERCAL
InterCaps
interesting
Internet
Internet Death Penalty
Internet Exploder
Internet Exploiter
interrupt
interrupts locked out
intertwingled
intro
IRC
iron
Iron Age
iron box
ironmonger
ISO standard cup of tea
ISP
Itanic
ITS
IWBNI
IYFEG