i started to reply to a comment from kate about where i find all the stuff i post and link to here, but my response grew to dissertation lengths, so i figured this subject deserved an entry unto itself.
the short answer is: everywhere, which is less than helpful. the long answer involves a review of my history on the internet from the early 90s, trolling hither and thither, accumulating sources. but, for the sake of clarity and simplicity, the following might be useful: first, let's say you find a blog or some other sort of source online that consistently posts links and things that you enjoy -- kottke is an obvious choice, so i'll use him to illustrate. over time, note the sources for things he posts that you like, and follow those sources (if provided; otherwise (or additionally) take the time to go through his links list (sites i've enjoyed recently, on the right-hand side of his main page), noting additional sources you like and following their links to their sources, and so forth, ad infinitum). eventually you'll sift your way back to a number of sites that consistently post stuff you find useful. there are also a number of sites/blogs wholly devoted to the task of link aggregation and tracking blog content -- things like blogpulse's top links and del.icio.us are useful in this way. through just rooting around and reading, you'll find a ton of others (and ones that aren't top-tier, obvious sources like boingboing or metafilter... and why anyone would post links to stuff gleened from those is beyond me, since the goal -- at least to my mind -- is to NOT be redundant).
other things that i've found helpful: 1. (to state the obvious) spending lots of quality time reading stuff on the web. though i doubtless benefit from link aggregators and the like, at least 1/3rd of the stuff i post link-wise are just things i randomly stumbled across through daily trolling; 2. being on a number of listservs whose members are rabid web scavengers. i've recently removed myself from a number of mailing lists because i just don't have the time for them, but there are one or two that i've been on since the 90s that are like goldmines full of webby goodness; 3. have friends and family who work on the web send you stuff -- my husband jamie, who works in web development, sends me web content-laden emails at least once or twice a week with the subject line: “post this to sweetney!”
all of which probably sounds like a lot of work and effort if you really aren't into it, i'd imagine. which is why i exist, living to serve, in all of my obsessive-compulsive glory! whee!
funny thing is, i don't really think of the links and such as an important part of the content of sweetney. they're just, well, there -- an amusing by-product of my weblife. i have no desire to have them doM_te this blog or what i do here, nor do i think i'm particularly cutting edge or pathfinding in terms of locating cool web shizzle -- there are people out there who obsessively devote every nanosecond to doing that, and i'm clearly not one of them. i *do*, however, know where some of those people live on the web, so i benefit from having that knowledge and access. and i pass the savings on to you.
/end long-winded over-explained web blather.