There seems to be a few land investment companies in the market at the moment. I don't think they are legally required to be regulated by the FSA which makes me suspicious.
Has anyone had any experiences (good and bad) with any particular companies?

I wouldn't touch most land investment companies with a barge pole - the business model too often revolves around buying up a piece of land which has no planning permission, and little likelihood of ever getting it, but is parcelled up and resold to "investors" on the suggestion that planning permission could be forthcoming, and therefore the land significantly increase in value.

The latter of which almost never happens.

There are far better ways to invest - land investment in the UK at least is too easily given over to cowboys.