I use it for surfing the internet with AWeb 3.5.08. It still needs a couple features of modern browsers like CSS, but it's faster than any browser on my Windows XP machines. Also, it's more immune to spyware and other hazsards since the Amiga is but a blip on the the internet.
So far, I have gotten it to burn CD's, play MP3's, MODS, and MIDI files, put it on my Windows 2000 network so that it can utilize shared drives and printers, and emulate a Mac (Quadra 650). I have also installed some programs, AmigaWriter, Art Effects, PerfectPaint DirectoryOpus and Bars and Pipes. I also installed some old software, ProWrite 3.2, DeluxeMusic2, Pagestream2.2.
I still have some more projects to do on it: Install TrueType fonts, a 3-D program (Aladdin 4-D, Imagine), some WB games, enable the USB ports, etc...
But this is as close to a modern Amiga you can get to today.
I do use WinUAE too. It's more compatible with classic Amiga software since it emulates the Amiga's custom chips. But in terms of performance, Amithlon blazes.
However, it does take quite a bit of tweaking. If you're up to the challenge, it will really payoff.