[sanswork]

Advertising is a fun problem space to work in. Huge amounts of traffic and data to process. Doing user prediction. All sorts of neat stuff. There are also a lot of smaller companies out there looking for good developers all the time. Get to know the industry and don't limit yourself to the top 5 and you can get in easy.

Stuff like profiles on users a lot of companies already do we also do stuff like predict based on numerous factors how likely you are to convert on different products. All this without you filling out a form.

Local ads are interesting but more work in selling. As for stuff like weightloss pills the reason you see so much of these is because very few sites can fill their full inventory with relevant paying advertisers so they put whatever they can in the spaces and keep their fingers crossed. The more profiling you do the less likely you are to find relevant advertisers.