The Server Robots are made by ALGOS CO. and come in several shapes and forms. They feature heavily durign "Season Three" and serve various functions such as managing the news feed of the user and applications download. During the movie Beyond The World, Makoto, an older model, plays a key role during the final battle.
A Server Robot can be seen in Iori´s room when she´s investigating the Lost Ones.
Ryuuji posseses a Server Robot called "Grid" which manages his department.
.hack//Beyond The World
During the movie, Makoto, Sora´s Server Robot, informs her that a new model is available but she doesn´t want to buy it. Later on, when Sora asks Makoto if "The World" is fun, he comes to the conclusion that she should try it herself and downloads the trial version containing the male PC "Kite" for her use.
During the climax of the movie, David uses Makoto to freeze the game, thus giving Sora the time she needs to get to Aura.