I have two
. One for my unRAID server + gigabit switch, one for my Mac Mini + display. My dad's also got one for his iMac + router + Comcast modem, so I'll still have interwebz if the power goes out. A poll would be awesome: have a UPS, don't have a UPS, planning to buy a UPS.
Edit: Oh yeah, the two I have are: APC Back-UPS ES550 and ES750. I bought the 750 a while ago, the 550 is more recent - it was on super sale for around $40 when I was looking for a plain surge protector, so I got that instead.