There's a ton of good software out there to help you accomplish many things on your computer; from PVRs to Office Automation to ... well, far too many to name. Even better, there's an awful lot of open source software available, so you don't need to spend a fortune to accomplish a task.
Being as there are, as mentioned, just too many great pieces of software out there to name, I'm just going to list some of my personal favourites.
MediaPortal - If you've got your own PVR, or are thinking of making one, MediaPortal can help transform your PC into a fully fledged media solution. There's a whole community of people making plugins for it too, so you can customise to your liking. The only downside is it's Windows only.
Kodi - If Windows isn't your thing, Kodi may be just what you're after. It's similar to MediaPortal in that it's media centre software, but it has the benefit of being cross-platform. I've actually converted from MediaPortal to Kodi now purely because of this. The fact you can install it on a Raspberry PI is a bonus (you can pick one up for about £30 at the time of writing - £45 ish if you buy a starter bundle), so you get all the benefits of a media centre on a 4 inch extremely low powered device.
Argus TV - Complementing MediaPortal and Kodi, Argus TV is a very competent recorder/scheduler application. I've been using this software for probably 5 or 6 years now and it rarely lets me down. It's not very complicated to set up. You will need a TV tuner card if you want it to record. It's clever, but it's not clever enough to pull terrestrial/cable/satellite programs out of thin air without some supporting hardware. This is Windows only software, which is a shame. The developer had hinted it was going to go cross-platform, but he seems to have been AWOL for some time now, which is a pity. Don't let that put you off though. There's a community that will try to help, and I can't imagine it'll stop functioning unless broadcasters make significant changes to the transmission spec.
VideoReDo - With the advent of PVRs and digital recordings, it's great to be able to edit the the resultant files and remove them pesky adverts. VideoReDo does a great job at this, and does it pretty damn quick too.
VSO Software - A whole suite of backup and conversion tools for multimedia content, some free, some not.
NewsBin Pro - If you download binary articles from newsgroups, you can't go very wrong with this great piece of software. Graphically it may not be pretty to look at, but under the hood it's a rock solid application, and while there are plenty of 'NZB only' options out there, if you want a bit more control, NewsBin Pro's just the ticket. Not free.
MultiPar - If you've downloaded anything from newsgroups, you'll know that most binary downloads come with parity repair files. Because of the way newsgroups work, and the differences between providers, it's quite easy to get incomplete files. This is where par files come in. While QuickPar hasn't had an update for years, MultiPar seems to be being actively developed. If you use binary newsgroups, this software is a no brainer. It's also useful for use on pretty much any other media content. I personally use it to protect my MP3s from corruption and unrequested editing by other software (Windows Media Player - I'm looking at you).
WinRAR - The need for a separate archiver for the average user is pretty much non-existent since Windows XP came out back in 2001 with support for .zip files. If you do need a bit more power and control though, WinRAR is probably the most popular compression tool out there these days, with support for far more and better compression types than WinZip. That said, if I hadn't paid for WinRAR years ago, I'd probably be using something like 7-Zip instead.
LibreOffice - Based on OpenOffice, LibreOffice is a free, fully featured, office suite. Regularly updated and works well with Microsoft Office documents, although documents with more complicated layouts can occasionally be a problem (think job application forms) although they seem to be getting much better now we've gone away from Office 97/2003.
Ultimate Boot CD - A collection of really useful PC diagnostics tools and applications. Whether you're a techie, or just a PC enthusiast, you should have a copy of UBCD as part of your arsenal.
Notepad++ - I mentioned this on right on the main page. While I originally began making this site using nothing but Microsoft's Notepad, it doesn't hold a candle to Notepad++'s source code editor. A fantastic piece of free software for any developer out there.
Well that's my introductory list. Most of the software on this page is free, and for the stuff that isn't, there's probably an open source version out there somewhere. You just need to go and find it.