I don't think points-for-no-ads is a good idea. The whole idea behind x10hosting is that it's a free service supported by ad revenue. If you can't find a place on your site to incorporate an advertisment, then you should fork over the money to pay.
As for the points-for-a-domain idea, I do like it, but it, like all the ideas requires a fail safe.
I was thinking about how to keep people from spamming, and I realized that that's exactly the reason why we have the 'reputation' feature. Anyone who subscribes to www.antionline.com
for example, knows that reputation is key in that community. You can rate posts depending on their content and relavence. If there was a way to implement a post rating system into x10hosting that may be another way to judge a person's contribution to the community. Users would rate posts based on their content, so anything that is blatently spam would be rated poorly.
So, for example, someone with 5000 points but a bad reputation/post rating wouldn't be able to buy a domain because they weren't responsible and submitting useful posts. So instead of relying solely
on points, make it a points/reputation combination.