As requested, here are a couple apps I use, have paid for, and swear at. Err, by. I’ve decided to break the entries down into: General Purpose, Writing, and Development. I’ve chucked each app, scientifically, into the group I probably use it most for, though it may apply to all the groups (or none of them). It almost went without saying, but these are all Mac OS X apps, and stuff I tend to use nearly every day.

OmniWeb – the bookmark management, tabs, textarea handling, and site preferences, in which you can set per-site user agent preferences are my big reasons for sticking with this one over Safari. But I’ve also been using this browser since 1996 on OpenStep, so it’s something I’ve always appreciated the fit and finish on.
Delicious Library – I had an app that never saw the light of day. It was a little bindings-based book tracker that could have been done easily with a spreadsheet or OmniOutliner or any number of other apps. But it was mine, it was called CharltonPublic.app, and it got me a sollid record of all the books I had to give away when we moved from the UK to Cupertino. And as soon as I saw Delicious Library I dropped that app like a sack of sledgehammers with a greasy handle. The scanner and Amazon integration sold me on this one. The checkin/checkout lending feature is also handy when my dad stops by and makes off with a few books.
NewsFire – A simple news reader. I love(d) the “Discover Feeds for Current Site in Safari…” when I used Safari everyday. But the recent(ish) fix to the default RSS reader behavior allows me to click the feed icon in the bottom right corner of an OmniWeb window and have it added to NewsFire, so no big loss. I also love the keyboard shortcuts to get around my unread feed items as quickly as possible. NewsFire’s simple interface had this one out on top over NetNewsWire (and definitely over PulpFiction). And that set of RSS tcl scripts from 1999 that I never turned into an app like I said I would. Doh.

Twitterific – Just been using this, and Twitter, for the last week or so. Pretty nice little unobtrusive app for monitoring activity on the ole Twitter.
iMaginator – From Stone Design. Which means… umm… “interesting” UI design, but just really, really cool engineering going on underneath. This one shows off Core Image’s capabilities.
Videator – From Stone Design. Which means… umm… “interesting” UI design, but just really, really cool engineering going on underneath. (Am I lazy or what? Copy and paste is your friend…) This one shows off Core Video’s capabilities.
OmniDiskSweeper – This is a nearly essential tool for any machine I’ve ever had, barring the iMac at home that serves mostly as a video and music content server. An excellent way (other than du -h -d 2 -c -x /) to find out what’s using up all your precious disk space.
OmniGraffle (Pro) – Great for what I’d have used Visio for in the past, layering text quickly over images, and, until OmniDazzle came along, marking up screenshots with circles and highlights.
OmniOutliner (Pro) – An excellent outliner tool. I used to use this primarily for engineering tasks, planning our wedding, weighing the pros and cons of moving back to Massachusetts and leaving behind a good job, you name it.
ecto – I’ve just recently (today) come back to ecto, after using nothing for a few months. And with my own ‘blog now set up on Supertart, posting images is so, so easy with ecto. The Amazon integration is nice, as well.
VLC – A really handy video Swiss Army Knife. Not in the sense that it’ll shred video files for you (though I could see how some celebs could want software along those lines), but in the sense that it’ll play nearly anything you throw at it.

All icons copyright or so to their respective developers.