Most of which doesn't apply to superhero games in general and ICONS in particular. Color is good, sure, but combat provides experience in only the loosest sense, and there aren't levels to be concerned about. You probably don't want the random encounter to be too hard, because you don't want it to steal focus from whatever you have planned for the evening.
The rolls for Champions disadvantages were a kind of random encounter that were personalized for the campaign: DNPCs, Hunteds, and Rivals were rare (8-), moderate (11-) or common (14-). If a particular disadvantage got rolled, it was probably going to show up somehow.
Bearing in mind these purposes (buffet assortment to see what the players want to follow up on; color; soap opera), here are some ideas for random encounters in a superhero game. I have included two combat situations, but only against minion-quality foes, so the PCs should make short work of them.
Even moreso than in other games, if a random encounter doesn't make sense in context of the game, don't use it.
|2d6 Roll||Random Encounter|
|2||Unusual type of minions (such as zombies shuffling out of graveyard for normal heroes)|
|3||Informed that enemy has escaped custody/been freed|
|4||Loved one tries to get closer to hero|
|5||Fan tells hero of approval|
|6||Uncomplimentary article or comment from member of public|
|7||Loved one explains new interest that could be a source of trouble later|
|8||Date with romantic interest|
|9||Hero has chance to do good deed|
|10||Persistent NPC fakes being victim of crime to get interview|
|11||Enemy publicly claims to have reformed|
|12||Loved one wants to break it off|
Obviously, there could be many more, but this is a random (ahem) sampling. You could subdivide it like this:
|1-2||1||Trouble at work|
|1-2||2||Good news at work|
|1-2||3||Extra obligations at work|
|1-2||4||One of the neighbours needs help|
|1-2||5||There's a superhero request and the person with PC is oblivious to hints about ending this conversation|
|1-2||6||A relative/old friend visits|
|3-4||1||Fan tells hero of approval|
|3-4||2||Someone fakes being victim of crime to get interview|
|3-4||3||Hero has chance to do good deed|
|3-4||4||Loved one has interest/new problem that could be a source of trouble later|
|3-4||5||Loved one arranges a date/party, possibly at a bad time|
|3-4||6||Loved one wants to break it off|
|5-6||3||Informed that enemy has escaped custody/been freed|
|5-6||4||Enemy publicly claims to have reformed|
|5-6||5||Uncomplimentary article or comment from member of public|
|5-6||6||Unusual minion spotted in crime (e.g., zombies in a street-level crimefighter campaign; plant monsters; etc)|