As for Mustacian advice ... PP had a great suggestion about getting used baby gear. In the US, there are a lot of semi-annual consignment sales that last for 2 days at a time. You can stock up on just about everything your baby will need in the next 6 months, for 70% off retail. E.g, a jumperoo that's usually $110 will be $25. It's especially true for infant gear, because it's used for such a short period of time that it's usually in great condition.
Do you know what you'll do for care when you return to work? Do you know how much it will cost? During maternity leave, I would automatically save the amount of the tuition each month. That way, you'll be used to living with that expense by the time you return to work. And you can put it towards building up your E Fund (if you need to) or debt payoff that will result in lower monthly bills or saving it for any future big purchases. Putting it towards retirement or paying down your mortgage are good too, but you may find that once a child is in the mix, you feel a need for more financial security in the sense that you want a bigger cushion or fewer monthly bills. (IDK your specific financial situation).
Explore the free activities near you -- playgrounds, libraries, walking trails, indoor playspaces at the mall or community centers, etc.
Find mothers' groups -- whether it's for breastfeeding support or moms in your neighborhood or whatever. If you can find some sort of affinity group, it may help prevent any stir craziness and it will be a great resource for you to see what other moms go through (the same kind of stuff you'll be dealing with!) It will also help build your repertoire or free things to do, like playdates at each others' homes. And, if the kids are different ages, you may find yourself the grateful recipient of lots of gently used baby gear ;)
I cloth diapered my son, and we plan to do it again for #2 (due in November!). If you have a washer and dryer at home (and a place to air dry is a big bonus), then it will take a total of 30 minutes out of each day to save a ton of money and the hassle of constantly buying diapers. Bonus if you make your own cloth wipes too. I think we'll do that this time around, since they'll just get tossed in with the cloth diaper wash. Although, we will probably have some wipes for the nasty jobs that we won't want to clean off the wipes! (sorry, is this getting too TMI?) All told, we spent somewhere around $900 on fancy diapers and detergent over 3 years of cloth diapering. Depending on how much you would spend on disposable diapers, this can save you some money. (I have seen estimates of $30 to $85 -- if you spend $30, you're only saving $200 over 3 years, but if you'd spend $85/mo, you'd save over $2k in 3 years).