This paper discusses key issues in the compilation of spoken language corpora in a computer-mediated communication (CMC) environment, using data from the Corpus of Academic Spoken English (CASE), a corpus of Skype conversations currently being compiled at Saarland University, Germany, in cooperation with European and US partners. Based on first findings, Skype is presented as a suitable tool for collecting informal spoken data. In addition, new recommendations concerning data compilation and transcription are put forward to supplement existing best practice as presented in Wynne (2005). This paper recommends the preservation of multimodal features during anonymisation, and the addition of annotation elements already at the transcription stage, particularly CMC-related discourse features, English as a Lingua Franca (ELF) features (e.g. non-standard language and code-switching), as well as the inclusion of prosodic, paralinguistic, and non-verbal annotation. Additionally, it proposes a layered corpus design in order to allow researchers to focus on specific annotation features.