Not pho, but Phnom Pehn is easily my favourite Vietnamese/Cambodian place. I've been going there for ... gosh... more years than I'm willing to admit to
Pho Van as mentioned is a good place. When I'm there though, I typically order the dry rice vermicelli with pork, spring rolls and veggies. I swear, it's an infinite bowl of food. Hits the spot when I don't want to be weighed down by salty broth.
Nobody has mentioned Buu Dien near Rupert and First, across the street from Blockbuster Video. Good subs - their grilled pork sub is, IMO, definitely worth killing for. About 5 years ago, Buu Dien had a killer sandwich shop at a stripmall on Fraser and 18th or so. Before it burned down, it rocked something fierce to the tune of 4 or 5 subs for $10! The subs at the Rupert location are still good but no longer as cheap.