You can try online dating sites and note explicitly that you're only there for friends; I've seen quite a number of profiles that indicated so (never mind whether that was indeed true or not).
I met a friend who I became close to on OkCupid, over a relatively short period of time, no romantic strings attached. Though she wasn't an aspie, she self-identified as highly-introverted like myself. I think disclosing one's status on the spectrum might be too much on a profile, but indicating one is an introvert seems to have worked favourably at least for me (with later disclosure when appropriate).
Good luck.
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Axis I: 299.80 Asperger's Syndrome, 314.00 Attention-Deficit/Hyperactivity Disorder, Predominantly Inattentive Type
Blog: http://www.23andaspie.com