This 370,000-sq-metre reserve encompasses three mountain-size granite boulders (the three sisters) ringed at the base by a forest full of ring-tailed lemurs. Anja's lemurs are famous for sunning themselves on the boulders (generally early in the morning); there are around 800 individuals in the reserve and surrounding hills and they're very well habituated so you'll get the chance to get relatively close. The reserve is a completely community-run initiative and has been extremely successful, generating revenues and jobs for the village.
Anja is not just one of the most enjoyable community reserves to visit, it's also one of the most successful in Madagascar. This means it sees around 14,000 tourists a year, so you are unlikely to be alone, particularly from April to November. Guiding fees cost a hefty Ar24,000/36,000/48,000 for 30 minutes/one hour/two hours. Some guides speak basic English (they know their script well but struggle with questions). Not only are you certain to see the ring-tailed lemurs up-close, but chances are you'll also find many different chameleons, including the thumb-nail-sized leaf chameleons (Brookesia) which, as the name suggests, spend their lives creeping through the leaf litter looking like oversized ants.
Anja is located about 12km south of Ambalavao on the RN7. There are regular taxis-brousses (Ar1000) from Ambalavao.