I started out using those hoops you tighten with a screw on the top (the hoops were plastic -- I never really liked the feel of the wooden ones). Then recently I discovered flexihoops and I love them! As I do mostly little stuff they are great to use.
However, the square flexihoop I got on the strength of liking the round and oval ones doesn't really work very well, very uneven tension. So I've been thinking of getting the smallest version (6", I think) of the square frame made of plastic tubes over which you fasten your fabric using tube-like clips (there must be a shorter name for these...)
Anyway, does anyone know the one I mean, and have you used them, and if so what did you think of them?
The roller frames look nice to use but tend to be too big for what I do. Also the sewing on of the fabric looks extremely fiddly, but perhaps those who use these frames have found differently?
Oh -- for very small work I just hold it

I did a dolphin in half cross stitch on 36ct linen as well, but because of the stitch type I did use a (very small) hoop for that. (I'll post a pic of the keyrings in my gallery.)