While nowhere as popular as Google, ask.com does have enough users I'd classify it as significant. Dunno if my site is typical, but I am getting 7% of the total hits I get from Google from ask.com. I rank very well in both these SEs. Only SE besides Google where I get more hits from is Yahoo. I consider ask.com sufficiently popular I'd be concerned that I was doing well there. Ask.com ain't like say Wisenut, where that site of mine didn't get one hit from last month.