Campaigning For Cross-Links
Mega-corporations do not need to campaign for in-bound links to their sites. Almost everybody else does. Links bring traffic directly to your site and improve your rating on search engines.
Links Bring Customers Directly
Depending on your product or service, the direct effect of good in-bound links to your site may actually be more important for its visibility than their effect on your search engine or directory ranking.
Path To Your Door, Not Highlighting The Door
For example, if you are already a market leader in a field, merely having links from all the sites that deal with that topic may bring you all the custom you can handle — in this case the links are merely providing an easy path to your door.
Breaking In To A Market By Highlighting Your Door
If on the other hand you have something to offer which is a competitor to current market leaders or to conventional products/services, your main concern will be to grab initial attention from those who are already looking beyond the mainstream — getting them to consider you at all.
If your primary motivation for getting links is to get your profile high enough to be even considered alongside your competitors, the links themselves may be less important than their effect on search engine or directory rankings.
Different Strategies For Getting Links
Building links to bring direct traffic themselves is a very costly and labour-intensive process. There is no point in getting links willy-nilly. You need to choose potential partner sites very carefully indeed. Ignoring the low-value ones entirely, whilst devoting thought and effort to selling the link to those sites that your prospective customers use regularly and care about.
Building links for mere visibility and kudos can be done, and is best done, using a scatter gun approach. All links are valuable to search engine ranking, so the cheapest to get or the ones with the most kudos themselves are the ones to go after. In either case, mass mailing and viral marketing will spread the message far and wide (at low cost). Most recipients will also have an interest in getting indiscriminate links, and many will oblige by swapping with you.