Top Surfer - Highly recommended.  A very responsive list. Create a free account and once you are logged into your account, look for "solo ads" and place your solo ads. Ad takes 8-10 days to run after it is ordered. 
http://topsurfer.com/getws.cgi?referer=lifetime

Traffic 9 - I highly recommend this site. I just ran a solo ad and received several paid sign ups from this site. Look for "solo ads" and place your order. 1 Solo Ad for $29 or 2 for $49 
http://www.traffic9.com/?ref=4946

GotSafelist - Voted #1 Safelist by TrafficHoopla. This is a very good place to join and place your solo ads. They are affordable at only $40. Join for f'ree and send a solo ad. 
http://www.gotsafelist.com/index.php?id=9045

Solo-ads - Another affordable site that gives you good traffic and paid signups. Visit the website and go to the left menu and click on "subscribe" and join as an affiliate. It's free and you will receive credits for a free solo ad. To purchase a solo ad, click on "ad rates" on the left menu of the website. 4,000 members - Cost $35 (on Sale for $25)
http://wetrack.it/soloads/af.cgi?2263

Rent-a-List - I highly recommend this site. They are very professional and I have received a lot of sales from running targeted email ads. They usually have a monthly promotion running - Never purchase advertising here unless they have a 40% off sale. I use the targeted email advertising - You get 50% G'uaranteed opens. Join f'ree and then login to back office and order. 
http://www.rent-a-list.com/s/i/lifetime
 
Supra-Ad - With new Herculist SUPRA-AD's, we will send your advertisement to the CONTACT and SUBSCRIBED e-mail address of 45,000+Herculist members! Purchase One SUPRA-AD Submission and Receive the
2nd Submission FREE!  Cost = $49
http://herculist.com/members/index.cgi?lifetime

ProbizTips - $197 per Solo Ad, $87 per Top Sponsor Ad, $37 per Middle SponsorAd

GetResponse Smart Ads - $299.95 per 100k Smart Ads, $199.95 per 50k Smart Ads, $99.95 per 20k Smart Ads.

Rim Digest - $149 per Solo Ad, $50 per Top Sponsor Ad.

Cash From Home - $99.95 per Solo Ad, $39.95 per Top Sponsor Ad.

BizWeb E-Gazette - $675 per Top Sponsor Ad, $675 per Middle Sponsor Ad, $360 per Bottom Sponsor Ad.

DEMC E-Magazine - $1,397 per Solo Ad, $227 per Top Sponsor Ad.

Web Marketing Today - $250 per 2-Line Ad in Web Marketing Today, $150 per 2-Line Ad in Doctor Ebiz.

Get Massive Hits Newsletter - $187 per Monster Package (1 Solo, 1 Top Sponsor, 2 classifieds), $127 per Solo Ad, $59.95 per Top Sponsor Ad.

Work At Home News - $99.95 per Solo Ad, $39.95 per Top Sponsor Ad.

Nova News - $197 per Solo Ad, $77 per Top Sponsor Ad. ($497 per 3 Solo Ads, $317 per 5 Top Sponsor Ads.)

Net Income Site - $60 per Solo Ad, $30 per Top Sponsor Ad.

Avenues 2 Success - $147 per Solo Ad, $49.95 per Top Sponsor Ad.

Tele Quest Link - $199.95 per Solo Ad, $120 per Top Sponsor Ad.

2 Bucks An Ad - $10 per ad to 10 Ezines ($90 per ad to 90 Ezines).

Sendfree Advertising - $47 per Top Sponsor Autoresponder Ad.

Online Exchange - $90 per Solo Ad, $40 per Top Sponsor Ad.

Nobo$$ - $1200 per Solo Ad, $250 per Top Sponsor Ad.

The Work At Home - $45 per Solo Ad, $40 per Top Sponsor Ad.

Straight Talkers - $50 per Solo Ad, $25 per Top Sponsor Ad.

Biz Site Biz - $55 per Solo Ad, $45 per Top Sponsor Ad.

Building Wealth News - $70 per Solo Ad, $40 per Top Sponsor Ad.

Dollarmines - $120 per Solo Ad, $50 per Top Sponsor Ad.

Bizsuccess Breakthroughs - $299 per Solo Ad, $129 per Top Sponsor Ad.

Axis Direct - $98 per Solo Ad, $68 per Top Sponsor Ad.

Complete Results - $2400 per Solo Ad, $1200 per Exclusive Newsletter Text Ad, $400 per Top Sponsor Ad, $250 per Middle Sponsor Ad, $150 per Bottom Sponsor Ad.

Promotion Tools - $22 per Solo Ad, $15 per Top Sponsor Ad.

All About Web Profits - $30 per 10-line Solo Ad, $25 per Top Sponsor Ad.

ClickBank Login Page Ad - $25 per day, $700 per month