Logitech Z-4 2.1 Speaker System with Subwoofer (Black) - Reviews
Pros: Small footprint satellites, decent bass
Cons: Sub is quite large, can be boomy.
For a 2.1 computer speaker set up that cost £40 (UK) this I think is as good as it gets. Decent range, strong bass when required, though can get boomy if placed incorrectly or the bass is whacked up.  Perfectly good for youtubing, games and impromtu listening sessions. Headphone jack on the control unit is a nice touch.
Highs can get quite shrill at the loudest, and doesn't have much in the way of extension up there, but importantly it can sound balanced at reasonable listening levels.