Adobe Flash and Reader run on Linux, and I'm not sure why anyone would want them. Flash is all right, but it's a closed-source application prone to security holes. Gnash and Swfdec, which are good FOSS Flash clients, both work well on a lot of sites including YouTube, though they gag on some sites. But then so does Adobe Flash, if you have the gall to be a point release behind.
Adobe Reader is for users who want a big fat bloated blob of spyware on their Linux PCs. KPDF, xpdf, and Ghostview are all excellent PDF readers, and Ghostview ignores any feeble Adobe copy protections. I have yet to find a PDF I could not read with one of these.
Photoshop? Give me a break. 90% of Photoshop users are not professionals; they have it only because they glommed pirated copies, and they feel all happy because they got an expensive program for free. They have no idea how to actually use it, and all the functionality they need is in Microsoft Paint.
Games? If the only thing a person uses a computer for is playing Windows games then Linux is not for them. Windows isn't either; they should be using a gaming console. A user who needs both Linux and Windows could do a smart thing, and that is use Windows only when they absolutely have to, and never ever connect it to any networks.
You can record up to 16 tracks at one time, and create any number of tracks until your computer keels over. You can edit and tweak multi-track recordings, and you can export to 5.1 and 7.1 surround. But if you're into heavy-duty multi-track mixing and studio wizardry, then Audacity probably doesn't handle it in a way that would be pleasing to you. It does not have individual per-track level meters or per-track notes and bookmarks, and it doesn't have the nice synchronization tools of powerhouse audio mixers and editors. For simpler multi-track editing it's fine.
Any audio hardware that works in Linux works with Audacity. Combine it with a real-time (rt) kernel and JACKD, the super-low latency sound server and audio router, and you have one sweet powerhouse digital audio recorder. I use it for recording my favorite band and making CDs, converting legacy media to CD, and a whole lot of other audio tasks. It makes beautiful high-quality recordings, and I wouldn't trade it for any number of fancy expensive commercial apps.