Are there many recumbant creeping cacti freely available for purchase?
I like the idea - I think it would add a different aspect to my proposed succelent garden, but not sure which species to start looking at.

I dont know about freely available RTG, but i know where i could possibly get a cutting of Trichocereus vollianus for you. Im not sure when i will be at the garden again but it will be this spring sometime. Ill try remember for ya

Echinocereus pentalophus would be worth checking out also, not only for it's sprawling habit but also it's brilliant flowers, can be a little tricky to get but not impossible.

There are a few others in this genus worth checking out too, ground cover wise.

Wouldn't mind a cutting of that one too PD. If available.

Echinocereus pentalophus and leonensis would be good choices, not very hard to find around here at all but of course availability varies regionally. these dehydrate considerably in winter and turn purple and aren't super attractive during this phase, but they reward will you some of the most magnificent flowers you can get cacti-wise. also super easy to grow in ground. a classic case of the ugly cactus with the magnificent flowers.
there are heaps of small low growing groundcovering Opuntiods to choose from.

oh and Mammillaria matudae! the call it 'snake cactus' or 'log cactus'. thats probs the best one i can think of. i have a small yellow one i posted a pic of somewhere.

(these arent mine)
http://images.google.com.au/images?hl=en&q=mammillaria+matudae&gbv=2

Hey Lewis - that mammillaria picture just made me spit my beer out. I had one of those ages ago. I didn't know what it was called and didn't know is was recumbent. I just thought I'd over watered it and it was on the way out

Thanks all - great suggestions.

PD - Thanks mate. Much appreciated again!

look into rats tail cactus, latin name escapes me, but they are often a pretty yellow/golden colour and grow fast along the ground and crest often as well!

^^Hildewinteria aurespina /aka Cleistocactus winteri i think. yes they crest regularly. nice flowers too.