Received payment today from 12by12Daily. Definitely a good site to be in at the moment.

2nd Dimension Ads is open for upgrades today only. According to The Zen's Den they haven't reached 500 members yet, so they are still taking new members, get in now.

Site Enhancements has added a new paid to sign up for a 10 cent bonus. After signing up, the paid to signup site will give you $1 for every member you refer. The site is also free to join. This paid to sign up appears to be a document about online marketing by marketing big fish Mike Filsaime. It's free & you get paid $1 for each referral, so take a look. Sounds like a very good read if you are serious about earning money doing online marketing.
Site Enhancements seems to be a good site to take a chance on with small upgrades. There are several different plans to choose from. You also get banner impressions and PTC with your upgrade package, so lots of good advertising here. Site Enhancements also has a good PTC section with a small paid to signup section. I haven't done any DD on Site Enhancements, but with all the advertising opportunities, the admin must be serious about the site. Daily cashouts are .01 minimum, so you have a good chance of getting your initial upgrade back, which helps minimize the risk.