The bartender also serves a purpose in Level 1 Treasure Trails. In some clue scrolls, he may be the person to give you your next clue, or he may give you your Treasure Trail Prize!
During the Bar Crawl miniquest, he is one of the Bartenders that you must get a drink from. His drink is the "Uncle Humphry's Gutrot". It costs 50 gp (You can only purchase if you are doing the Bar Crawl) and lowers Attack, Defence, Strength, and Smithing, doing up to 20 life points. It also makes you throw up.
The bartender also seems to be one of the few NPCs who are aware that RuneScape is a "computer game". This is an example of a character "breaking the fourth wall". When players inquire what the bartender means by this, he makes a brief attempt at explaining what a computer is, calling it a "magic box". However, the player is baffled, and calls the bartender's idea "obviously mad".