Shimon Sandler wrote a controversial post about the options available to sites who cannot actually make code changes to optimize their site. He explains that you can build links, and that's perfectly legitimate as it's called "off site optimization."
The question is: does that really help "optimize" the site at all? If the website was poorly coded, will those links really help? Probably not.
Sphinn forum member JohnHGohde notes that this is not SEO at all:
The most positive comment that I can come up with is that link building is called SEM, rather than SEO.
In other words, SEO (search engine optimization) is about optimizing the site, but SEM (search engine marketing) includes all the other factors, like link building.
Further, if you're only going to optimize based on links, you're probably Google bombing. This reminds me of when the SEO community tried to rank Stephen Colbert as the Greatest Living American Dude. That's not the way you're supposed to do it, according to forum members. Further, it can be really difficult to rank at all with a poor quality site; Jill Whalen calls it an "uphill battle."
Other people believe that you can still optimize your site with link building, but that if you do that, you're not doing the complete job. Hugo Guzman says the following:
The proof is in the pudding. It's been done countless times (link-building without site-side). That said, not optimizing site-side elements is definitely an incomplete approach to SEO.
Like I said, Shimon's post was really controversial -- but there are a lot of great comments.
Forum discussion continues at Sphinn.