lets see... dreamhost was mentioned above... I've been a happy dreamhost customer since 05. The thing about dreamhost is that its cheap hosting. I use it for a few blogs, some forums I made for friends, nothing essential, and nothing to do with my business. For a casual user dreamhost is good. I will agree with mreed about dreamhosts ability to deal with high volumes of traffic. Over the past three years I've had pages linked from fark twice and slashdot once. Not a hiccup, which is amazing for $8 hosting.
On the down side, dreamhost goes out from time to time, often for long periods of time. The worst outage I've had to deal with there is a three day outage about 18 months ago. No refunds for outages, and no tech support phone number. As long as you don't expect tech support, or uptime, its pretty good. Don't get me wrong, I'm not complaining about the lack of tech support, its $8 hosting and I will continue to host there as a backup storage place as long as I'm in this business (plus they allow adult sites!). If you do want to try dreamhost, use the coupon code MickeyClicks to get your setup fees waived.
Now on to business hosting...
The cream of the crop, the best host I have ever used, hands down bar none is Rackspace. Rackspace has the best sales, customer and tech support of any host I have ever used.
Last fall one of my clients had an emergency, one of his servers which held the traffic management script we used was in a datacenter in California, in the middle of a forest fire. I access to the server was intermittent and I was unable to stay logged in long enough to get anything off of it. I spoke with my client and explained the situation and he decided we needed to get another host. He asked me to find the best host available. I called Rackspace, gave them a link to a backup on a remote server and they took care of the rest. They configured our software, and then our support group went and learned all about the operation of our custom software so they could support it for us. Just top notch all they way, call at 3am and get a live person and get transferred to some one in your "support group" that is already familiar with all of your servers and systems. Just amazing. This is the hosting equivalent of buying a bentley. It carries a price though... When I switched this client over to Rackspace their basic plan started at $300/month.
Now for something in between... The company I host almost all of my non-adult sites at is Mediatemple these guys are great. 24 hours telephone tech support, root access, high bandwidth, high availability servers. I've used their grid hosting and their DV hosting services and have no complaints. The basic plans at MediaTemple start around $20/month and make for a great entry level host. Due to the way their grid system is setup, if you outgrow the $20 plan you can just add more processors and ram as needed.
So those are the hosts I have done business with and will continue to do business with.
If you deal with adult and need dedicated hosting, Webair isnt bad.
The ugly? Ipower. I cant find one nice thing to say about ipower. Don't ever host with these guys or buy domains from them it will haunt you for years. Even now I wake up with nightmare that my credit card has been charged for hundreds of domains I no longer own... and then I wake up and it isnt a dream and I have to spend a few hours on the phone getting it straightened out. I had to report my CC as stolen and get a new one with a new number just to get away from these assholes.