I have not used Paypopup. I hate popup and popunder ads. But i think, yes you can use paypopup along with adsense.
I'm pretty sure AdSense has written a limit of popunders per session into their publisher terms. I suggest you read their terms and email them for confirmation. As for paypopup, I've been working with them for a few days now, they seem reliable.
you can use popups/unders.i think it is 2 per session,but yeah read the terms. should you use paypop.com? NO!!!
yesup.net owns clicksor and paypopup. low pay,if you get paid and they are known to have installers/trojans.
I'm testing them right now on my machine, one popunder every 7 minutes. It's been running for two days and I've seen no installers or trojans. Every single popunder they've served that had an ad in it (they redirect to one of my pages if there is no inventory) I've been credited for. I fail to see why everyone complains about them.
I run Clicksor and i am loving it. In Google Adsense, i didn't earn over a $1 even after some 80-100 clicks. But, with Clicksor, i have earned $2.5 so far from some 50 clicks.
you can use paypopup with adsense but there is a limit on number of popups per session so make sure to read it . regarding paypopup , I used them months back and they werent gd at that time but now as checksum is saying , they might have improved . So , give them a shot .