I searched for "digital cameras" on my site using BOSS.

The result url for the #1 result:
www.shopzilla.com/10J--Digital_Cameras_-_cat_id--402
The clickurl for the #1 result is:

http://lrd.yahooapis.com/_ylc=X3oDMTU4bDVrMnM3BF9TAzIwMjMxNTI3MDIEYXBw
aWQDYzVOcDFVclYzNEhLUXhodHZFY1ZTMTJKMlRBek5yYV9SRHBoeUp1b0ltVG1BeTh6Um
pER2xaOXdfUHRsYUVrLQRwb3MDMARzZXJ2aWNlA1lTZWFyY2hXZWIEc2xrA3RpdGxlBHNy
Y3B2aWQDNWlHVDVVTGFSV3owaFVXenE3SGRCQURfVEE0cW5FanlmM0lBQ0dXVw--
/SIG=1hjoj5kfe/**http%3A//rdrw1.yahoo.com/click%3Fu=http%
3A//shopzilla.g.delivery.net/g/ue/c/%253Fe%253D62%2526v%253D13509%
2526l%253D10109%2526r%253Dhttp%3A//www.shopzilla.com/10J--
Digital_Cameras_-_cat_id--402__kw--%25253CDI_SM_KEYWORD/%
25253E__mkt_id--26888656__qcid--%25253CDI_RAND_NUM/%25253E__rf--mlp%
26y=040AB5C4584D063350%26i=1473%26c=21808%26q=02%255ESSHPM%255BL7%
257Bvxvk~s%253F%257C~rzm~l6%26e=utf-8%26r=0%
26d=wow~c5Np1UrV34HKQxhtvEcVS12J2TAzNra_RDphyJuoImTmAy8zRjDGlZ9w_PtlaE
k-en-us%26n=LNKKK1K9EFP4HGP0%26s=5%26t=%26m=48F27F72%
26x=0574E8614C5EC959F8C474D9CDDF62BFFA

As you can see, in the middle of that url is: shopzilla.g.delivery.net
If you surf to www.delivery.net, it says it is the advertsing company
Acxiom Digital, and refers you to: acxiomdigital.com. From there, you
can click on: SEARCH ENGINE MARKETING
http://www.acxiomdigital.com/services/search.asp
At the bottom of that page:

Pay-for-Placement

Acxiom Digital Pay for Placement (P4P) management services are built
to deliver performance-based results for your search engine
advertising budget. Our expertise in keyword selection, text ad copy
writing, bid management, geo-targeting and other advanced
optimization features will produce a measurable return on your
campaigns.