it is not possible in search network but is possible in content network, are you interested? What countries/regions are you targeting?
If your information free yup i interst Visitor targeting from USA and Canada or other no problem. you can help me?
Create an empty adgroup (no keywords yet), but add a lot of ad creatives to it (the max you can) Use the Adwords Editor for creating several Adgroups clones from this adgroup - use the copy/paste on "Ad Group tab" to clone one or more adgroups. go back to the web interface and use the keywords tool to go filling the empty adgroups witth the more keywords you can - the 2000 keywords limit per adgroup is your limit. on the next keep monitoring to replace the keywords of adgroups with: - poor conversion or - low traffic this is it