[w/e] "Whatever"

[W/O] "Without", predates Internet

[w00t, woot] Leet-speak exclamation of excitement or happiness or applauditory whistle; […]

[w012d] "Word" (a generally positive interjection)

[W8] "Wait"

[WAD] "Without a doubt"

[wade in] or [wade into] {v.}, {informal} 1. To go busily […]

[wade through] {v. phr.} To read through something long and laborious. […]

[WADR] With all due respect.

[waffles] Pun on "[ROTFLMAO]"; used similarly. In full: "Roffle my waffles"