1/100 sites

[chan2020]

There are many sites that offer free adveritising.  But, you can't get better in the bux sites. Most of them don't survive.
You need to think about sites which gives $0.00002/click.  There you can get many offers for free advertising. 
Ex:
10000 banners
500 ptc(2)
100 ptr(2)

If you really want to get referrals and sign ups under you, you need to advertise there.

I will give you the list of sites they really give you free ads offer.
Just you need to sign up and request your free upgrade.  Normally you will get your free ad offer within 2 days.
It's the best way to advertise without spending money.
When you account has been upgraded, clickSubmit upgraded ads link and then submit your ads for free.
I will give you the list of sites with amount of free ads they offer.

http://www.sweetclickers.com

5000 banners(2) monthly
250 ptc(1) monthly
Paid E-mail for all(7 days)

http://www.schoolbusofcash.com
10000 banners(4)monthly
250 ptc(2) monthly
Paid e-mail(5 days)

Other sites listed below just gives the same type of offers.
http://www.vegasbux.com
http://www.cashavenue.net
http://www.mysticsclicks.info
http://www.guardianmails.com
http://www.somethingelse-mails.com
http://www.crazy-mail.com
http://www.linksandthat.com/

edit: ref links removed

[nitinkumar]

x-mails.biz also give free monthly advertising. You just need to request. Free upgrade last for 6 months.

[chan2020]

I think you are the admin of x-mails.biz

[nitinkumar]

I think you are the admin of x-mails.biz

Sorry for late reply.

Yes I am admin of x-mails.biz

[mark63534]

Is there like a full list on these that I can select from online?

[ranjiths]

nice info. Thanks