0% Balance Transfer: $21,500 Approved!

Wow, I just decided to go all out on a 0% Balance Transfer offer, and it went through. Well, I actually asked for $25,000, but looks like I could only get $21,500 approved...But wow! I didn't expect that much. Chase sent me 3 offers, one in December, one in January, and then one in February. Each extending the 0% for up to 15 months! No balance transfer fees. So with the offer in February, I took it. I requested $25k transferred to my Citi card, where I then requested a check for the balance. I always transfer to another credit card from a different company. Why? I don't know actually...I guess first of all, I don't want them to tell me I didn't do a "balance transfer" and second, if it's another company, they can't see if I really have a balance. Hopefully by my next net worth update, I'll have the cash sitting in one of my accounts...What can I do with $21,500 for 15 months...hmmmmm.