WEGCash is my top sponsor right now.
they pay weekly on time, all the time. i've had 2 late checks from them in a year, and they were only 1-3 days late.
they have 42 sites which you can promote at free trials, $1 trials or $2.95 trials.
they also have several join4free email sites which pay up to $1.50 per email. i have an average conversion ratio of 1:8 for the last year.