U-Line has the best ones for the money in my opinion. We have a dozen or so of these in different sizes. Make sure you get the 5/8" thick version. The difference between these and nothing at all is night and day.

[Link: m.uline.com]

They also have anti-static anti-fatigue mats should your application call for it. We have a couple left on-site and grounded. Obviously more costly and overkill for your everyday use. The one linked above is very nice; choose your size and 5/8".