dashboard.html

<li data-row="1" data-col="1" data-sizex="1" data-sizey="1">
  <div data-id="random_aww" data-view="RandomAww"></div>
</li>
<li data-row="1" data-col="1" data-sizex="1" data-sizey="1">
  <div data-id="animalsbeingjerks" data-view="RandomAww"></div>
</li>

reddit.rb

require 'net/http'
require 'json'
 
placeholder = '/assets/nyantocat.gif'
reddits = { 'random_aww' => 'awww', 'animalsbeingjerks' => 'animalsbeingjerks' }

reddits.each do |title, reddit|
  SCHEDULER.every '60s', first_in: 0 do |job|
    http = Net::HTTP.new('www.reddit.com')
    response = http.request(Net::HTTP::Get.new("/r/#{reddit}.json"))
    json = JSON.parse(response.body)
 
    if json['data']['children'].count <= 0
      send_event(title, image: placeholder)
    else
      urls = json['data']['children'].map{|child| child['data']['url'] }
 
      # Ensure we're linking directly to an image, not a gallery etc.
      send_event(title, image: urls.select{|url| url.downcase.end_with?('png', 'gif', 'jpg', 'jpeg') }.sample(1).first)
    end
  end
end

Seems like a decent solution, since the server is just pushing data to the client it would be tricky to do anything else.