I'm not sure anything will run on under a watt, but you might talk to Fritz from Fritzspeakers about building you something with a 4" Fostex driver. I have a pair and they are excellent, although I've never tried with that much of a fleawatt. But if your amp has a pair of stereo (rca) outputs, you can use any powered speakers. In fact, even if it doesn't, you can probably use the headphone jack with a splitter and powered speakers. Maybe get a pair of Tannoy powered monitors.
Looking for any speaker recomendations for a sub flea watt amp
I have in the last six months added a nice headphone rig to my main system and just recently separated it bringing it upstairs into my office using it quite a bit more as a second system, with that said I would like to add a pair of speakers to listen to in near field for my wife as she is in the office doing her work, she loves music but is very intimidated by the all tube system we have in our living room and does not even consider turning it on or off. The system in question consist of a Yamamoto Soundcraft HA-2 headphone amp rated at 240mv at 8ohms and yes it does have speaker taps. Am I just pissing in the wind or are there some speaker choices that might satisfy my need and if the answer is no it will not hurt my feelings because I am very satisfied with the system as a headphone setup and have been using it a lot as such.