Here's 3 relatively mild yet simple blackhat techniques with parked pages. One I've never seen mentioned before, but is so obvious I'm surprised nobody is doing it but here goes:

1. Go to any wifi hotspot, my favorite is downtown or near apartment buildings where there are many unprotected ones to latch on to.
Then proceed to click a few ads, change your IP, then click some more, never exceeding 2 or 3 clicks a session.
The trick is to alternate browsers and fake the user-agent as much as possible, as well as keeping the times of day random if you can

2. Use an autohits system like sh*alom. They're spammy as hell, and can possibly even cause your pc to get spyware, but if you use a linux PC, and let it go all day, you'll not only get lots of impressions but people sometimes click too. Not sure what the referers look like for this personally, but I've been doing this every day for 8 months and nobody's complained to me about the traffic

3. My favorite is unclickable links. Goto some really popular forum or picture post site with comments and just post your site using hxxp:// instead of http://. This means that the person has to copy-paste it into the address bar, and convert to http to check out your site. This forces type-in traffic. The number of visitors and conversions might be lower than posting a clickable link, but you just have to find a way to mass post it at various places and it works wonders.
I have a few crons running every 5 minutes that post to several message boards using CURL that do this for me. It brings in a few hundred visitors daily per site.