Add option to mark yourself as: online, away, busy, or offline in your guild member roster. (Your friends list has this option, why not guild member list?)
Guild Wars Patch message color should be changed to yellow, orange, red, or something other than green. (Many messages are green and it not aways very eye catching.)
Guild Member suspension option. If a guild leader feels that a member was in the wrong, but not enough that they should be kicked out of the guild completely. The member would still be in the guild, but would lose cape, not be able to listen or chat in the guild chat, and be locked out of guild hall while on suspend status.
Weapon sets annoyance. When you use weapon sets the weapon shouldn't take up any of your inventory space.
Disable the Windows key while playing! (the key between alt and ctrl)
Minor Suggestions
johnnylange