I've been perusing a few posts here and there, and one thing that sometimes confuses me is seeing an 'l' and thinking that it is an 'I'. An example is the question about ClF3 ($\ce {ClF3}$) which I know is obviously NOT CIF3 ($\ce {CIF3}$) but which managed to confuse me for a minute or so nonetheless. I guess the other fonts that cause problems are ones where 'l' looks like '1' such as many monospaced fonts!
Really, I guess it's a fairly minor thing, but I was wondering about what the rest of you guys thought?