Squarefree.com has been hosted at DreamHost since November 2001. I like DreamHost because for $10/mo, I get more than 120GB/mo of bandwidth along with all the features I need. (Sign up with promotion code squarefree to save $77 on any yearly plan; I'll get $20 for referring you.)
The thing I like most about DreamHost is that it charges extra for resources such as disk space, bandwidth, and non-shared IP addresses, but most features are free with any account. I haven't had to pay extra for the features I use: .htaccess, ssh, MySQL, phpMyAdmin, Analog, Apache log access, custom DNS records, Jabber and mail addresses @squarefree.com, and announcement lists. DreamHost even has a cool backup feature called snapshots.
Another thing I really like about DreamHost is that the plan I'm on keeps improving. For example, in December 2004, DreamHost tripled everyone's bandwidth allocations, taking mine from 30GB/mo to 120GB/mo. I had never exceeded 30GB/mo, but at one point I reduced the number of posts in my RSS feeds in order to avoid overage charges. (DreamHost originally described the bandwidth-tripling as a promotion that was extended to existing customers, but since it has lasted for over four months, it seems permanent.)
The only host I know about that would give me more than 120GB/mo for less than $10/mo is PowWeb (mentioned in a host poll), which offers 5GB/day for $8/mo. But since PowWeb's bandwidth allocation is per-day rather than per-month, it's only better than DreamHost's 120GB/mo if a site's daily variation in bandwidth is small. If squarefree.com only had 5GB/day, it might have survived the traffic spike around the release of Firefox 1.0, but it would not have survived being Slashdotted when I released Adbar, and it would not have survived me mirroring crashreport.wmv in order to add it to my del.icio.us bookmarks. Both events used 10GB within one or two days.
DreamHost's support, while not consistent, is usually excellent. The DreamHost knowledge base, along with Google, answer many of my hosting support questions. Also, since many people use DreamHost, searching Google with "dreamhost" in the search phrase often helps me solve problems. When I do contact DreamHost support, they respond to all of my questions within 24 hours. I get fast and helpful responses even for esoteric questions, such as a problem I had with piping tail -f through two greps. I get answers for most outage-related questions within an hour, although those responses are sometimes of the form "it seems to be working now" rather than an attempt to help me ensure my site doesn't break again.
DreamHost allows adult sites (contrast PowWeb, Pair). I don't know if Pair or PowWeb would consider squarefree.com an "adult" site due to Thumbs and Pornzilla, but with DreamHost I don't have to worry.
DreamHost even has a sense of humor. The monthly newsletters, which are written by co-founder and Harvey Mudd College alum Josh Jones, are often hilarious. Another example of DreamHost's humor comes from their support form:
There are two things I don't like about DreamHost.
First, Gallery, Movable Type, and WordPress all seem slow; I haven't figured out why. (Update: WordPress and Gallery no longer seem slow and I am no longer using Movable Type.) Second, they don't use mod_speling, saying it would be too much of a performance hit. (Jakob Nielsen could remove an entire section from his 404 page if he used mod_speling, but he doesn't use it, so DreamHost could be right about the performance hit.)
The final thing I like about DreamHost is that they give me $97 if you sign up after clicking a link from my site (unless you use the promotion code squarefree, in which case you save $77 and I only get $20).