These are Additional 2nd tier email traffic sources and solo ad sources.
I have not used all of these sources personally.

Abel Chua http://www.abel-chua.com/solo-ads/

Alex Fields http://www.redpointprofits.com/solos/

Andrea Smith-Fulton http://smokinhotsolos.com/solo

Anthony Tilley http://www.anthonytilley.com/solomailings/

Ashley Gough http://ashleygough.com/soloads/

Atheer Fendi http://atheerfendi.com/solo-ads

Beatrice Brown http://bbprofits.com/Soloads

Bilaal Hussain http://www.internettrafficmethods4u.com

Brocha Weiss http://explosivetrafficvideos.com/solo_ads/

Cal Champlin http://www.calchamplin.com/solo_ads.html

Chris Jenkins http://onlinesuccesswithchris.com/soloads/

Colin Meunier http://www.colinmeunier.com/

Colm Wynne http://www.colmwynne.com/SoloAdSale/

Craig Raphael http://www.esourceinfo.com/advertising.html

Dean Miles http://www.dean-miles.com/soloads/

Dennis Pippen http://ads90.com

Emilis Strimaitis http://www.strimaitis.com/

Formidable Marketers http://formidablemarketers.com/solo-ads/

Frank Gang http://frankdang.com/soloads/

Frank Salinas htp://franksalinasonline.com/soloads/

Gary Baker http://opportunity-advisor.com/soloadbooking.html

Gedas http://www.solo-store.com

Gina Reedy http://book.safe-swaps.com/ginareedy

Heimir Finnson http://heimirfinnson.com/solo-ads/

Holly Sutton http://www.hollylorene.com/soloads/index.html

Igor Kheifets http://www.crossingthefreeline.com/soloads.html

James Neal http://realjamesneal.com/realqualitysolos/

Jayson Benoit http://jaysonbenoit.com/solo_ads/

Jeffery Baxter http://mastermindlistbuilding.com/soloads.html

John Cornetta http://www.soloads4sale.com

JT Martin http://jtlikes.com/soloads/

Kelvin Nikkel http://kelvinnikkel.com/soloads/

Kenneth Kraakstad http://kenneth-kraakstad.com/soloads.htm

Kevin Fahey http://isellsubs.com

Mark Gurney http://www.onlineprofitsinc.com/soloadinfo/

Mark Lyford http://lyfordmarketing.com

Natalia Piterova http://properebooks.com

Phil Springer http://rapidprofitplan.com

Phillip Brewer http://www.imspecialty.com/MySoloAdOffers/index.html

Randy Harris http://solosforsale.com/

Ray Johnson http://www.ray-johnson.co.uk/soloads

Rodger Hyatt http://www.rodgerhya.com/solo

Sean Story http://www.rapidsuccessformula.com/soloads.html

Steve Bermann http://singingsteve.com/solo.html

Steve Lorenzo http://ezinesoloads.net

Thomas Burke http://fasttrafficboosters.com/SoloAdMailings/

Vicki Nguyen http://www.thebestsoloads.com/vicki

Vince Craine http://vincecraine.com/solos/