Completely agree on the Aquaclear. Possibly consider an AC 70 or even a 110 to allow more room (to put a heater and media in). You can mod the impeller to slow the flow but you may not need/want to do that as the filter turnover may provide all the flow you need for a 7.5 gallon (no bulky powerhead needed in the tank). You can also swap the AC 70 impeller with a AC 50 impeller without modding anything. The length of the drop tube might be of concern but I am fairly certain you can cut those to fit. You can also check inTank for their AC parts (nice media baskets, etc.). If you do need more flow with the filter, +1 to the koralia nanos.
Click on the filter size and it will give you some products that work with the filter...
http://shop.mediabaskets.com/AquaClear_c44.htm
The 110 media basket that hold a tunze 9002 skimmer is expecially nice. Saw one of these in person not long ago...
http://shop.mediabaskets.com/AquaClear-110-Media-Basket-Fits-Tunze-9002-AC110MRX.htm
A PAR 38 type bulb may be worth looking into. These screw into any standard light fixture. However, unless this will be an SPS dominant tank, I think it will be too much light for that little tank unless you hang it fairly high above the tank.
http://www.marinedepot.com/LED_Light_Bulbs_for_Saltwater_Reef_Aquariums-FILTBULD-ct.html
http://www.ecoxotic.com/ecoxotic-par38-aquarium-led-lights.html
Other option is the ecoxotic pro module. As long as you don't plan on going SPS or clam route, you should be fine with any LPS or softies. I would get the blue/white (10 to 12K) model and possibly add a all blue pro module or a all blue stunner strip (cheaper and less wattage). Note the stunner strips alone will NOT be enough for any corals. You don't want a ton of light overt that little tank or you will fry your corals.
http://www.ecoxotic.com/panorama-pro-module.html
http://www.ecoxotic.com/stunner-led-strips.html
By the way, not to point you to another forum but here is a nice Mr. Aqua 7.5 build you may want to look at...
http://www.nano-reef.com/topic/284749-maestros-75g-mr-aqua-build/