Found this tonight, seems decent from first experiments so thought id share …
http://cpetry.github.io/NormalMap-Online/
and their texture generator (handy for making heightmaps as well)
http://cpetry.github.io/TextureGenerator-Online/
updated resource page :
Worth popping on the wiki for the free/cheap resources Daz?
Yeah think so. so far so good, only just found them tonight. hoping if a couple of peeps have a play around and get a general census
Cool - will add it to my list of things to do! 
ill play with it for a couple of days and see, then ill update the Wiki page in the lounge.
You are a 
p.s. had a quick go, looks really good… I had a UK map spinning around on the cube, and later some lovely looking cobblestones… appears to work well (only tried the top link)…
Thanks for sharing the tool!
Have you tried Crazybump for maps and such? Works really well!
http://www.crazybump.com/
Or, if you have Photoshop (don’t know about Gimp)
https://photoshoptrainingchannel.com/photoshop-3d-depth-maps-bump-normals/
Dont have photoshop im afriad 
as far as i could tell CrazyBump isnt free (but it used to be, before the days where i thought i could use it). i did look at AwesomeBump as it was free, but it looks like Crazy is the new Awesome but with a few quid attached…
but the texture generation side of it seems fairly decent
I’mScottish so I’m naturally afflicted to spending any money at all lol
Oh, so it is true about the frugal nature of Scots winks
I run a mac so I am use to using the Public Beta Test portion. Didn’t even check out the windows version. Sorry about that! Is a bad girl tonight! 
I had completely forgotten about AwesomeBump. Oh, another product that does decent maps is PixelPlant https://www.pixplant.com and is less expensive than CrazyBump. I believe the Free Lancer version is $49.00 USD. I purchased it for creating seamless textures then realized, after the fact, it does maps so was a win win for me.
had a play for a couple of days. and ive updated WIKI page.
for the normal maps, its a bit of a trial and error, it seemed to work pretty well for most things i threw at it, and for a free tool if you done have access to other image manipulation tools/filters etc it will more than suffice for prototyping and testing, and you can get all the AO / Spec / displacement and Normal maps from it.
when I was trying it, best to stick to a power of two texture to use. some things wont turn out correctly, but for the most part I got decent results.
Didnt try using the photo part of it, so ill leave that for someone else to try…
looks like its still getting developed, but, ive used it a couple of times to get some cloud textures and used them of varying strengths to get a nice and quick water effects, and the B/W heightmaps are pretty useful to use for a quick procedural terrain for unity for prototyping.
all in all a handy couple of free tools to speed up testing iterations to see how things look…
Awesome review Daz, and thanks for updating the wiki!