At work I generally use a laptop with an external monitor. This is usually fine; email / specs / documentation on the laptop screen and my dev tool on the external monitor. Sometimes, though, that just won’t do.
To get round this, I snaffled a spare monitor from a recently departed contractor’s desk, and got myself a USB-to-SVGA adapter from Amazon – this one, actually:
Whilst it’s never going to be mistaken for a ‘real’ graphics card, it does an OK kind of job on largely static things. You can definitely tell it’s a little plastic box though – updates are a bit jumpy, and if you’re a quick enough typist you’ll actually ‘feel’ the delay. But, it does the job I got it for perfectly; I can look at big complex specs on one monitor, and make them into real breathing code on the other.
7/10. Or maybe 8 if you really don’t want what you’re displaying to move, ever. 2 if you want it for watching videos (tip: you don’t).