You can use Wiki Markup in Comments (and other fields where it is activated (I think you can activate it in the field config but I am to lazy to look after it right now :D)
If you look at the relevant documetnation of the wikimarkup (https://jira.atlassian.com/secure/WikiRendererHelpAction.jspa?section=images) you see that you can add some images.
It doesn't support all file types but to add the usual snapshot to a ticket it is enough :)
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