Is having mutiple sites under on hosting plan good for SEO?

[shakim]

I am creating simple 1-2 page websites that don't really take up space. Therefore hosting them individually would be wasting space and money. Waht I proposed was signing up for 1 hosting plan and divide that space up for each site. Here are my options:

1. Create sub-domains and have the registered domains point to the subdomain and mask it.

2. Create sub folders that will house each site and forward the registered domain to the index page inside the sub folders and make the url.

3. Addon domains. Where everything resides under on hosting account but the sites are seperate.

What kind of effect will options 1 and 2 have on SEO? Will all the pages get crawled together and do I place robots.txt file inside each folder?

[tcady]

I alos have this problem, my opinion is there is no way to keep the spiders form crawiling the main doanin, there for you will have what appears to SEs to be mulitple sites with the same content - one at the main hosted domain, and one at the sub domains.
I believe I am being penalized for this very thing and am trying to figure out what to do.
But in answer to what is the result - you CAN be penalized, though it doesnt happen at every SE.
On some SEs, both my doamins are listed, so I might have the #1 spot with one domain and the #3 spot witht he other domian which is rather cool, but it is also spamming in my opnion, though not on purpose.
But I agree with SEs for not allowing it. The situation was this way before I came on board to manage these domains, and it is not easy to just change it due to the way things work here.

[shakim]

From what I understand it is best to keep everything seperate. After reading alot of forums and tutorials I think the best way to approach this is to have addon domains. From what I understand SEs treat them as seperate sites all together as long as you don't cross link.