You can roll the lump sum into an IRA, then use a portion of that IRA to buy an immediate annuity from an insurance company. Don't confuse this type of annuity with the ones people use as tax-deferred investments. An immediate annuity is a vehicle designed to start paying you a guaranteed income as soon as you invest your money. In effect, you've created the same sort of monthly income stream that you would have with the lifetime annuity option on a pension.
The advantage to this arrangement is that you get the security of a monthly check, plus you have a stash of money that can keep pace with inflation and help out with occasional unexpected expenses.