online? the best online php resource is the php documentation itself.
I know a few 'off the shelf' books that are very good..
"Be conservative in what you send; be liberal in what you accept." -- Postel's Law
"tacos" -- Cactus' Law
"t̥͍͎̪̪͗a̴̻̩͈͚ͨc̠o̩̙͈ͫͅs͙͎̙͊ ͔͇̫̜t͎̳̀a̜̞̗ͩc̗͍͚o̲̯̿s̖̣̤̙͌ ̖̜̈ț̰̫͓ạ̪͖̳c̲͎͕̰̯̃̈o͉ͅs̪ͪ ̜̻̖̜͕" -- -̖͚̫̙̓-̺̠͇ͤ̃ ̜̪̜ͯZ͔̗̭̞ͪA̝͈̙͖̩L͉̠̺͓G̙̞̦͖O̳̗͍
why not php's site? I looked around for a while, and that seemed like it was the most thorough, even for beginners.
If your friend is really serious about learning PHP it's best to actually buy a book as they're much better (usually) than what's available online.
the "quickstart" guides have always been sweet for me, I have the html, java and php (4) ones. i dont know if they released an updated one for php 5, but i still reference my copy a lot. that combined with the php.net manual, and i havent had anything that took me more than 5 mins to figure out
"Ignorance is bliss, for stupid people."
"open-source is [...] programming Darwinism."