This server still sees some activity, although the majority of it is within the guilds. You might see some people in a tavern some evenings, but other than that there isn’t much random RP happening.
That being said, there’s The Botany Band on Alliance (not sure if there’s anyone else these days), who are quite friendly.
On Horde you have:
Convocation of Elrendar: Mainly blood elf RP, but other races are welcome as well I believe.
Wayward Vagrants: Mercenary/shady business RP. All kinds of characters are welcome.
Hand of the Titans: Leans more towards hero-RP. All kinds of characters are welcome, although “darker” characters, like warlocks, DKs and void users, might not have a good time.
The Beastmaw Warband: Horde military RP. I believe all kinds of characters are welcome.