Hoople - 8:00 pm on Apr 6, 2011 (gmt 0)
I have two seasonal sites I built and maintain for a local non-profit. They both are 'brick-n-mortar' in that one has to visit the location the enjoy the use of their 'product'. One is related to a little animal usually focused on around now and the other is about a big person normally thought of at the end of the year.
In the beginning I harvested all the competitors backlinks. I collapsed them into a single listing by domain with a field listing the number of links found (total of all competitors) at that domain. I sorted by that number to order the list for that link acquisition task (2004?).
I then got creative on searches by playing with some really different keyword searches. Relax a bit more than normal and stop assuming. Many of my best search ideas came from trusted friends - 'how would you search for a April widget site?' I found a wide variety of sites, forums, groups, blogs and such. At first I asked them for reciprocal links but now (since 2009) I only do so if they require it.
To expand on what I found above was a lot of highly ranked on topic personal sites that were built 'back in the day' (1998) that had lots of links that were in my niches topic neighborhood. A member here 'wheel' suggested going for links in niches that touch your niche - I also do this and plan to do this more in the future.
Ignore the Google bashing here and make use of the 'Blog', 'Related Sites' and 'Discussion' search choices. There's a lot of low hanging fruit out there. Creates a real head slapping moment. Blekko, a new search engine makes it easy to surf through your niche's neighborhood and find related but non-competing sites. Click your listing's 'links' and then in the results the 'links' of the serps. Ignore the somewhat staleness of the results.
Look for dated articles in your niche that make you say 'Gosh, I wish they would update it [and put my site in there too]. If you find one that ranks well - ie it has some Google Toolbar PR, they show up in Alexa and their top Keywords ranks well in serps) rewrite it with update and send it. I've done 3 of those in the last 18 months. They were used AS IS. One even gave me a secondary byline with a link! BTW don't dwell on Toolbar PR - I use it only as an indicator of 'no penalty' and some or a lot of site trust.
There are a few current threads here on WW about broken links. Look at the authority sites, personal sites and directories in your niche for them. Write a personal note to the owner requesting your site to replace it. Don't make them work - copy their anchor link and description style. I've got a few I never though I'd get this way.
Directory wise go for DMOZ, BOTW, on topic niche directories and regional directories and then stop. Resist the urge for free/paid directory listings as recent Google changes make them MUCH less valuable. Instead spend all your time on the items suggested above.
Lastly go the the Library section of this forum. Read the older posts for some real helpful posts. Ignore the dates on them - almost all of the advice given is timeless and still applies!