I run a small blog(in my free time), specific to a software package that is written in 2 different script/programming languages. Same concept, same process, same screens.
Someone always links to it. I never ASKED, EVER. The "small" projects that I do via that blog(people ask for paid help) after visitors read the articles will always outweigh any amount that I could make via the ADs if I would place any, SOMETIMES double digits.
DO I link to other resources on the web that are mentioned in my work? ALWAYS and NO Trickery. I follow one simple rule: If I was searching for an answer related to my study/work/theory and found it useful after all, I will link to it the best way I possibly can if it passes “WHITE-HAT Sniff Test”.
DO I share my user base usage of the site with anybody, NEVER. I get tons of requests to put ADS on this site by hosting companies, language specific software firms - text links, Flash ADS(LSO), image ads and so on... I think too much data sharing could only hurt the site. Give it all away and it is only a matter of time till the SERP Controller drops you like a rock as soon as they see an opportunity.
But it's just me and I don't envy the SERP anymore to the point that I used to, for the site in question...