It can be done - and a lot of people are doing it.
I would not suggest setting up a 10 gallon reef as your first saltwater reef tank - but then again - who am I to discourage you from trying.
Here's a neat link on nano tanks - good luck !!! http://www.wizard.net/~nemo/nano.htm
it's very possible but very difficult. The reason it is so difficult is because the slightest mistake of adding to much chemicals or salt or something like that can be much more drastic then if u did it in a 120 gallon tank. Good luck though.
thanks for the quik responses and thank you eric for your coral and fish ideas!
if you guys know anything about puffers please tell me about them cos i think i'll make it a puffer tank!!
please i need your advice!