A reader points me toward this post by Hilzoy from October 2006 about some of Obama's wonkier endeavors:
...my little data point is: while Obama has not proposed his Cosmic Plan for World Peace, he has proposed a lot of interesting legislation on important but undercovered topics. I can't remember another freshman Senator who so routinely pops up when I'm doing research on some non-sexy but important topic, and pops up because he has proposed something genuinely good. Since I think that American politics doesn't do nearly enough to reward people who take a patient, craftsmanlike attitude towards legislation, caring as much about fixing the parts that no one will notice until they go wrong as about the flashy parts, I wanted to say this.
She lists some of the legislation. Hilzoy is also currently sifting through Obama's and Clinton's legislative records to see what they have actually accomplished while in the Senate. As far as his speechmaking goes, here is a post of mine from early January listing some of his more substantive policy speeches.
On this note, Ezra Klein has a novel idea:
...presumably, the way to figure out if [Obama] was talking about policy was not to evaluate whether his speech was longer and more boring than his other speeches, but to examine the actual statements he offered and ask some experts how the proffered solutions might fare.
When all else fails.