I bought 10 Epson EMP S4 projectors for school I work for at summer 2006.

Epson EMP S4 is updated (in 2006) version of EMP S3. Epson's EMP S(x) line of projectors is design to suit mobile and office users. And it does it perfectly.
It's small (33X25X9cm) and light (2.6kg). It comes with small remote control and a bag with shoulder strap.
It's brightness (1800 ANSI lumens) and resolution (800x600) is sufficient to display presentation (text, photos and short movies) at 2-6m distance onto white wall or whiteboard (usage professional project screen will improve image brightness and sharpness) in bright room.
It has three types of video inputs (15 pin VGA, S-video and composite video input), so at the same time three devices can be connected. Switching via signal sources is very simple, remote control has three default buttons (computer, video, composite), each one for different device display.
Focus is manually adjustable next to lens. It has vertical keystone (+-30; must have in modern projectors) and display can be electronically shifted off centre up, down, left or right (about 10% of it's width/height).
Projector has build in mono speaker (audio signal input by double audio line-in), but not loud (only 1 Watt) so it's usage is limited.
Bulb life cycle is 2000h in normal mode (does anyone use economic mode at all?) which is standard in that price range. Replacement bulb is about £120, and is dead easy to fit in.
Epson give 3 years warranty for S3 body and 90 days for lamp. In my opinion, it's fair deal.

All projectors are ceiling mounted in classrooms, 2.5 to 4m from whiteboards (in two cases Smart-boards) on which they project image. Each is connected to classroom PC (VGA input) and DVD/VHS combo player (composite input). For sound I use separate speakers system; build in speaker is way to weak for classroom full of kids.
I have to say that projector extremely well cope with difficult, classroom environment: lots of abuse from users, frequent turning on/off, temperature changes, vibrations, staying switched on for whole night etc.
Very easy to set up; just connect cables and turn on. Using remote control choose source of signal, adjust display using focus and keystone. Ready to go.
It's easy to use, warms up in couple seconds, turns off in 3 seconds after pressing button (great advantage for portable projector).
However, there is no rose without thorns. It has two major downsides, which make it nearly useless for home usage (tried it):
- fairly loud cooling system;
- display resolution is too low for DVD quality movie watching.