I wish people would stop preaching about how much better water based lubes are over petroleum based lubes. They really are not THAT good for anal play. Vaginal play, yes by all means but NOT anal play.
Fact is, water based lubes dry out quickly no matter how much the label tells you it last longer than anything else. this makes it tricky for anal play because when you're really into it and your partner is thrusting like mad, you may not notice the friction that is building up in your ass until it's too late. Petroleum based lubes stay slick MUCH MUCH longer that any water based lube and is therefore safer for anal play.
Yes, they do break down latex and rubber so just be advised. That said, I've been a huge butt plug and dildo fan for years and can now take toys that are over 3 inches in width. i didn't get there by using water based lubes though. They were never slick enough to get me past my limits and into the next size up so before I started experimenting i used vaseline for years on my rubber and latex toys and I'm sure they broke down the materials but not to any extent that was noticeable.
These days I use creams like "Vaseline Intensive Rescue Moisture Locking Body Butter" as well as this cream... The only difference is that the body butter is thicker and comes in a tub where this one comes in a pump bottle.
http://a1468.g.akamai.net/f/1468/580/1d/pics.Drugstore.com/prodimg/157894/200.jpg
It's a nice balance between water based and petroleum based and it smells great!!! It stays slick for a very long time and when combined with J-lube it is incredible but I do reapply water to keep everything slick the entire time I play!!!!
If you want a really good lube then try silicone lube. Stays slick for hours and great for ass play BUT it is very expensive and just like petroleum based lubes break down rubber and latex, silicone lubes will break down silicone toys. By how much??? Who knows.
Lastly, it doesn't matter what kind of lube you use for ass play, if you are stretching your ass out to take VERY WIDE toys or just trying anal sex for the very first time then you will definitely want to use lots of lube and always reapply even if you think things are going along smoothly and you don't need it. Trust me, this will keep you from having a sore ass the next day.