I pay them as soon as I get them, assuming that by paying them I keep a small cushion until next payday. If they are too large (very rarely), I wait until next payday.
I do some online bill paying, but I mostly use online accounts to watch my bank balances - on-the-fly reconciliation.
I've been doing online transfers to savings, savings bonds, DRPs (first rule of savings: you are a bill and you're paid first!). Gotta watch for fee charges though...in some cases I've run across a buck or two ACH fee. Remember, its gotta be cheaper than the 37 cent stamp!