For Memory. Crucial, Corsair are typically great. Lots of folks also like OCZ as it is usually less expensive.
Kingston is a known brand, and tends to be okay if you get their higher end chips.
As far as motherboards go. I've had a couple Asus brand motherboards over the years and they've always been great. Seen a lot of good reviews and such for Gigabyte (Asus' main competition).
My current motherboard is made by XFX (it's an nVidia based board though). They just replaced my board under warrant, so I'm happy about that.
Everything depends on what you're doing though.