Ovi Store Games - Online Multiplayer
Bobba
Bobba is a virtual world for mobile phones made by Sulake, the creators of Habbo. Bobba is intended for a slightly older audience than Habbo, and has more mature Sims-like graphics.
Fridge Magnets Touch (aka Fridge Magnets)
A connected application which lets you interact with random strangers around the world by moving fridge magnets on a shared screen.
Lexulous Crossword Game
Lexulous is the new name for the game Scrabulous which was a big hit on Facebook. It's essentially the same game as Scrabble but using a different name. The name "Scrabulous" caused legal difficulties for the publishers as it was so close to "Scrabble", so they changed it to "Lexulous".
Reversi Online
This is a version of the classic board game Reversi (aka Othello), but with a number of playing options: online multiplayer through the internet, hotseat multiplayer by passing a single phone between two people, and offline single player against the phone's AI. There's also an online league table.
Tibia Micro Edition
Tibia ME is the world's first Massively Multiplayer Online RPG for mobile phones, which takes place in a real time fantasy world shared with thousands of other players. It's been operating since 2004, and has built up a cult following in the mobile gaming world.