re: Poker & What time of day do the fish bite best?
Weekends, night time... varies by site, because some have more players from particular parts of the world, but basically you want to be playing against the recreational players and drunks.
One simple measure I'd guess would be checking how many people are on the site at different times - when there are the most people on the site that's when the non-full-time players are on there - the recreational players. When you've got the minimum number of players on there it's more likely to be those that are on a lot of the time, at a guess.
Of course, finding a table with some spoilt rich person who's got time on his hands could happen during those quiet times... so it's probably better to check the tables to see flop percentages, aggression rates, etc... rather than expecting to get a good table at a specific time.