One of the things I'd add right now - you mentioned the interlinking of internal pages, which I agree helps - what will add to that is since most people here are doing galleries and free sites underneath their root domain sites, is to make sure you get those little sites linked individually by DMOZ in the proper cat. With the number of directories worldwide (including Google) that use that directory, its a huge boost in backlinks and a "trusted" link.
I hear a lot of people moaning that they can't get listed in DMOZ, and while there were some problems recently with the admin side of the directory, most people that I know that submit there regularly do get listed. There are some rules given in the submit pages and its very important to follow them to the T - things like not repeating a word between the title of the site and the description (seems little but it will get the submit deleted) - not reading the "what type of sites belong in this cat." page etc.
Its just like following the rules for submission to a LinkList - pays to follow them.
With just six of the larger linklists and a DMOZ link, you can pretty much rank in the top 10 for phrases with less than 100k page results in Google "almost" every time. There are some small exceptions where someone has spammed the first 20 listings, but that normally doesn't happen where the resulting SERPs are less than 100k
Back to the original tip though - since you have good links coming into those internal pages, and you interlink and linkback to your root, you help move that linking importance around.