You all know that for the past few months a lot has been updated on the Vault, including a new icon feature for commenting on blog posts such as this. Bethesda has a few (Not exactly for this purpose, of course) icons on this page. If none of these are to your liking, you can use some from the wiki itself, make your own, or simply search the web. Thanks.
A How To on Icons:
1.) Download the desired file to your computer.
2.) Go to Preferences at the top right drop-down menu.
3.) Under the User Profile tab (The starting tab), click browse to go through your files to find the icon.
NOTE: The file you choose cannot be larger than 100x100 pixels and must be downloaded to your computer in order to choose it.
Keep on helping out!