Harman Kardon HKTS-18 5.1 Channel Speaker System

The speakers sound great with my HD DVD and Blu-ray players. Incredible bass. Consider setting up your A/V with front and surround speakers set to "large" - that works great with my Sony amp. The surround speakers look especially good when installed in a corner due to their triangular shape. I was a bit sceptical when I read that it came with its own mounting hardware (espcially since I already had universal mounting that I could use), but it was easy to install, and looks/works great. I also purchased the H/K stands for the front speakers, which also look great. All-in-all, this is quality through-and-through.

Philips HTS3555 Home Theater System with iPod Connectivity (Black)

This is a great surround sound system, and easily fills my 19' x 17' living room with sound. The only drawback is that the speaker wires are integrated right into the speakers, and into custom inserts for the unit. So, to change the length of the wires, you have to splice them instead of just buying new, higher grade wire. It also means you can't upgrade the wire, of course.

Sony DAV-HDX500/i BRAVIA Home Theater System

Very pleased so far. Sounds great, plenty of power to rock your media room, and was easy to set up. There's an on-screen setup feature that lets you easily customize the setup for your particular room configuration. An included microphone lets you do a push-button fine-tuning of the sound relative to speaker placement. It's cool to see the system report exactly how far all the speakers are away from the microphone.
I also purchased the wireless surround kit from Sony. Setup for this was also pretty simple, and was supported by the HDX500 system.
Remote is typical Sony - lots of buttons. But fairly intuitive thus far.
The digital media port works well with the different generations of iPods we have in the house. On-screen graphics are very rudimentary, however, which is a big departure from the iPod interface.
There are a bunch of different sound fields that could be better described in the on-screen system or in the manual.

Sony BRAVIA DAV-HDX265 Home Theater System

I spent weeks listening to high end audiophile systems and was dismayed to learn that to be happy with these systems I had to spend over $3000 on amp and 2 speakers, which I had no intention of doing. On the way home I bought one of these for under $300 and was shocked to find I liked it better!
The sound is quite good, amazing on DVDs and very good on CDs. The speakers are attractive and unobtrusive. However, there are some drawbacks:
1. no digital audio input. Multi-channel audio is limited to the built-in 5 disc changer, no chance for upgrading to new DVD formats or to connect a digital input from a satellite receiver.
2. the style of the main unit left me wanting something different (your tastes may vary)
3. the speaker wire uses proprietary connectors- need a few more feet than are included in the box? you'll be splicing.
4. I read that the digital audio connector to computers only plays windows formats- no iTunes connectivity.
5. The 5-disc changer loads one at a time and takes a long time to switch; I found myself forgetting what was in each slot and it took a long time to switch around and find out.
But, like I said the sound is very good. So if you can live with the feature limitations this is a very very good deal for the price.

Onkyo HT-SR800 7.1 Home Theater Entertainment System (Black)

As you can see from a quick search this is almost always reviewed highly and is also highly rated by Consumer Reports. I recently got my own and I wasn't disappointed. The system was easy to set up and a quick browse through the instructions gave me all the info I needed. I have listed the 3 most common complaints about the system below.
1. The HDMI is just a pass through you have to connect the sound to the unit separately (not really that big a deal).
2. The included wire is too thin: this is true you can replace it cheaply with wire bought on Amazon, so its not devastating. I recommend the METRA Ltd S14-100 MTA 14 Gauge Clear Speaker Wire which you can get here for $21.53 and will really improve things.
3. Onkyo doesn't make speaker stands for this system and the speakers only have keyhole style brackets on the back for mounting which can make buying wall brackets difficult.
I'm not positive how to resolve this, B-tech makes some screw in mounts you can put in if you dont mind putting some wholes in the speakers B-TECH BT1 Universal Speaker Bracket for Small Speakers (Pair per box). They also make a wall mount that clamps the side of the speakers if youd prefer not putting holes in your new speakers B-Tech BT77 Speaker brackets Black.
But both of those solutions are kinda expensive (30 per pair for screw in, 70 per pair for the clamps).
I recently bought some universal mounts (Premier Mounts PSPK-5B Universal Speaker Mount for Walls and Ceilings with 2.5-Inch Extensions (Black)) that supposedly work with keyholes so we'll see.
UPDATE: the speakers are great, make sure to use the microphone to calibrate, this is part of the value of the system and makes a big difference in the sound quality.
About the mounts:
The cheap universal mounts, were ok.
They worked fine on the Satellite speakers but there were some design flaws and they don't have the strength to hold up the big front speakers. One of the pieces broke during assembly but as I had 5 and couldn't hang the front speakers with them anyways that wasn't too big of a problem.
I used the 29.99 B-Tech mounts mentioned above (the ones that have to be screwed in) for the front speakers and they worked perfectly. Enjoy!