and by the way: It DOES detect eicar
Now needed: Support for scanning packed files (inside zip files, not 100% needed though as they arent that dangerous when packed

), support for scanning a single file, support for doing a running-processes-and-their-modules only scan (i miss that from av's!), on-access scan (not needed 100% atm), scanning packed and protected files (use a pe-identifyer to see what kind of packer they are using. If they use things like MEW or so thats often used to compress trojans, instead of a virus alert throw in a heuristic warning that it CAN be a trojan. Simply unpack upx packed files to a temp dir, and for other packers try some generic unpackers they might work. Grap a look at programmerstools.org)