Custom widgets
When the library doesn't have the widget you're imagining, build it. Custom widgets are your own sidebar panels: your content, your layout, rendered with the same safe template language Custom Templates uses.
Creating one
In Appearance, then Widgets, create a new custom widget.
Give it a title, the one members see on the panel.
Write its body. Plain HTML is enough for a links panel or a Discord button; templates with variables are available when you want live board data in there.
Save and place it in your sidebar order like any other widget.
What people build
A links panel: the rules, the Discord, the wiki, the current event topic.
A welcome box for guests, selling the community in three lines with a register button.
Seasonal panels: the advent calendar, the tournament bracket, the charity drive thermometer.
Custom widget content is sanitized the same way templates are: no scripts, safe HTML only, and anything broken falls back gracefully. You can't hurt the board from here.
Custom widgets pair well with a bulletin strategy: the bulletin announces this week's thing loudly and temporarily, the widget keeps the standing links quietly and permanently.